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CROWN  AND  BRIDGE-WORK 


FOR  STUDENTS  AIS^D  PRACTITIONERS 


BY 


FREDERIC  A.  PEESO,  D.D.S. 

UIRLCTOlt  OF  THE  DENTAL  GKADUATE  SCHOOL  OF  THE  UNIVERSITY  OF  PENNSYLVANIA, 

PHILADELPHIA 


lllugtratcD  wltb  732  cnaravinas 


LEA    &    FEIM(4EI{ 

J'H  i  l,.\  I)I;M'II  I  A    AND    N  i;  W     ^()|{K 

I  •»  1  (i 


a.- 


Entered  according  to  the  Act  of  Congress,  in  the  year  1916,  by 

LEA  &   FEBIGER, 
in  the  Office  of  the  Librarian  of  Congress.     AH  rights  reserved. 


TO  MY  BEST 
FRIEND    AND    COLLEAGUE 

ARCHIBALD  C.  EGLIN,  D.D.S. 

IN    GRATEFUL    RECOGNITION    AND    REMEMBRANCE 

OF    THE    STIMULUS    AND    INSPIRATION 

RECEIVED    FROM    HIM 

THIS    VOLUME    IS    RESPECTFULLY 

DEDICATED 


PREFACE. 


The  technic  of  Oowu  and  Bridge-work  has  assumed  far  more 
importanee  since  dentists  and  physicians  have  reahzed  the  close 
rehition  of  oral  cleanliness  to  the  patient's  physical  Avell-being 
To  secure  a  full  measure  of  stability  with  promise  of  long  service, 
with  the  restoration  of  function  in  mastication  and  speech,  was 
once  considered  the  aim  and  end  of  successful  Crown  and  Bridge- 
work. 

Though  all  careful  dentists  appreciate  the  importance  of  accurate 
workmansliip  in  attaining  these  desirable  results,  and  that  these 
])rostlietic  appliances  should  be  so  designed  as  to  facilitate  clean- 
liness, the  announcement  that  some  cases  of  Crown  and  Bridge-work 
which  had  fulfilled  all  mechanical  requirements  had,  nevertheless, 
proved  a  serious  menace  to  the  health  of  the  patient,  came  as  a 
rude  shock  to  the  dental  profession. 

Errors  in  judgment  or  workmanship  in  repairing  injuries  to  the 
natural  organs,  or  in  treating  their  many  pathological  conditions, 
are  usually  local,  and  are  readily  seen.  Recently,  attention  has 
been  directed  to  the  possibility  of  serious,  even  fatal,  ])athol<)gical 
lesions  arising  from  unseen  and  unrecognized  conditions  developed 
under  Crown  and  Bridge  constructions  which  had  been  worn  with 
comfort  and  satisfaction,  aiul  apparent!}'  were  well  designed  and 
well  made.  That  they  were  the  cause  of  the  trouble  in  the  un- 
fortunate cases  reported  was  reached  only  by  a  process  of  excluding 
otiicr  probable  causes.  The  proof  was  furnished  by  the  conditions 
revealed  on  their  removal  and  the  rapid  and  c()nij)letc  recovery 
which  followed. 

This  has  prompted  the  writer  to  give  special  attention  to  this 
aspect  of  the  subject.  The  troul)le  justly  complained  of  is  not 
iiilHTcnt  in  Crown  and  Bridge-work  construction  itself — it  is  due 
entirely  to  errors  of  judgment  in  the  selection  or  i)reparation  of 
supports  or  abutments,  and  .'ivoidabN-  errors  in  designing  an<i 
constructing  tlic  ajjpliances. 


vi  PREFACE 

The  writer  desires  to  enforce  the  most  exacting  care  in  all  pre- 
paratory procedures  to  ensure  a  healthy  condition  of  the  supports 
and  abutments,  and  thoroughness  in  the  mechanical  preparation 
for  all  attachments.  If  these  are  accurately  fitted,  and  are  strong 
enough  for  the  work  demanded  of  them,  and  the  requirements  of 
occlusion  are  fully  met,  he  feels  assured  that  the  appliances  will 
prove  aseptic,  durable,  and  efficient. 

In  formulating  and  presenting  to  the  profession  the  methods 
found  satisfactory  in  practice  in  the  preparation  for  and  con- 
struction of  Crown  and  Bridge-work,  he  has  borne  in  mind  the 
paramount  importance  of  a  well-considered  aseptic  technic  in 
addition  to  that  required  to  meet  the  mechanical  problems 
involved. 

A  long  experience  in  private  practice  and  in  the  teaching  of 
this  dental  specialty  has  enabled  him  to  select  and  present 
methods  readily  acquired,  that  produce  results  quickly  and  with 
certainty,  if  carefully  followed.  He  would  add,  however,  the 
caution  that  it  requires  long  and  patient  practice  to  thoroughly 
master  the  details  of  operations  which,  although  common  to  the 
dental  workroom,  when  applied  to  Crown  and  Bridge- work  are 
more  exacting,  and  call  for  a  more  skilful  use  of  tools  and 
appliances  than  when  used  in  constructing  ordinary  plate  work. 

The  author  cannot  conclude  without  expressing  his  apprecia- 
tion of  the  assistance  given  by  Dr.  Wm.  H.  Trueman,  and  especi- 
ally Dr.  Edward  C.  Kirk  and  Dr.  A.  C.  Eglin,  whose  inspiration, 
constant  interest  and  encouragement  for  several  years  past  have 
been  largely  responsible  for  the  production  of  this  volume. 

He  also  wishes  to  express  his  gratitude  to  Mr.  Christian 
Febiger,  whose  patience,  courtesy  and  many  kindnesses  have  done 
so  much  to  lighten  the  work. 

F.  A.  P. 

New  York,  1916. 


COIs  TENTS. 


CHAPTER   I. 
Artificial  C'uowns .•      •        ^' 

CHAPTER   II. 

P\THOIOGir\L     CoN'OtTIOXS      IN      THEIU      RELATION      TO     CrOWM      AND 

22 
Bridge-work 

CHAPTER  III. 

Crown  and  Bridge-work  in  Relation  to  the  Vitality  of  the  Pulps 

IN  Supporting  Teeth  ' '^•^ 


The  Pulp  C> 


CHAPTER   IV. 

.....       40 


CHAPTER  V. 

Relative  Strength  of  the  Teeth  as  Supports  for  Bridge-work         72 

CHAPTER   VI. 

Typical  Shapes  of  the  Teeth.     Mechanical    Preparation   of  the 

Teeth  AND  Roots  for  THE  Reception  OF  THE  Bands     ....       78 


Impressions  and  Models 


CHAPTER  VII. 

.      .      .      120 


CI  I A  ITER    VIII. 

li,  iLDi.NG  IP  Broken-down  R<.ots  with    Amai^ciam    Puhpakatouy  to     ^^^ 
Crowning 

CIIAI'TIIH    IX. 

.     ,     .     \r,{) 

Prostmesls 


viii  CONTENTS' 

CHAPTER  X. 
The  Making  of  the  Crowns 187 

CHAPTER   XI. 
Bridge-work 205 

CHAPTER   XII. 
Removable  Bridge-work -. 225 

CHAPTER   Xni. 
Tubes  and  Split  Pins 276 

CHAPTER   XIV. 

Methods     of    Using     Porcelain     Crowns    with    Cast    Bases    in 

Removable  Bridge-work 301 

CHAPTER  XV. 
Retaining  Media 336 

CHAPTER  XVI. 
Repairing  Crowns  and  Replacing  Broken  Facings 342 

CHAPTER  XVII. 

By  Howard  T.  Stewart,  D.D.S. 

Bridge-work  Designed  for  Rigg's  Disease  Conditions   .      .      .      .     351 

CHAPTER  XVIII. 

By  Louis  J.  Weinstein. 

Dental  Metallurgy 357 

CHAPTER  XIX. 
By  Fred'k  K.  Ream,  M.D.,  D.D.S., 

AND 

Richard  H.  Riethmuller,  Ph.D.,  D.D.S. 

The    Uses    and     the    Value     of    Radiography    in    Crown    and 

Bridge-work 408 


INTKOnUCTlON. 


Although  crown  and  bridge-work  has  come  down  to  us  from 
remote  antiquity,  it  is  only  within  the  hist  three  or  four  decades 
that  it  has  assume<l  an  imi)ortant  place  in  dental  prosthetics.  In 
the  beginnino;  of  this  revival,  most  of  the  work  was  done  in  a  hap- 
hazard way,  with  but  little  or  no  understanding  of  the  principles 
involved,  and  with  but  little  api)reciation  of  its  requirements,  its 
possibilities,  or  its  dangers. 

The  sole  idea  of  the  dental  practitioner  was  to  give  the  patient 
something  better  than  the  i)artial  plates  then  in  use,  something 
resembling  more  closely  the  lost  natural  teetli  in  firmness  and  in 
abihty  to  i)erform  their  normal  functions. 

Crude  as  crown  and  bridge-work  then  was,  it  was  sufficiently 
successful  to  be  appreciated  by  the  community,  and  to  be  considered 
by  the  profession  as  promising  greater  usefulness  than  the  appliances 
it  supplanted.  Patients  demanded  it,  and  this  prompted  an  earnest 
effort  on  the  part  of  many  in  the  profession  to  discover  and  remedy 
its  shortcomings.  As  the  result  of  this,  within  a  few  years  crown 
and  bridge-work  has  earned  recognition  as  a  specialty-  in  dental 
science. 

As  often  happens  when  new  things  are  introduced,  or  old  things 
are  so  revolutionized  that  they  enter,  quickly,  upon  a  higher  stage 
of  development,  the  limitations  of  crown  and  bridge-work  were 
but  slowly  recognized.  The  importance  of  firm  and  healtliN-  supports, 
due  consideration  of  the  mechanical  principles  in  designing  and 
construction,  careful  attention  to  occlusion,  and  work  that  was 
thoroughly  aseptic,  received  but  little  thought  during  the  early 
days  of  crown  and  })ridge-work.  As  a  result  the  work  was  usuallx 
short-lived,  was  not  cleanly,  and  the  appliance  was  not  always 
comfortable  or  effective. 

Looking  back  to  this  period  in  the  development  of  crown  and 
bridge-work,  viewing  the  monstrosities  in.serted  by  thoughtless 
enthusiasts  as  dental  bridges,  or  reading  the  records  of  disappoint- 
ment, failures  and  disasters,  one  wonders  how  the  art  survixcd. 


X  INTRODUCTION 

That  it  did  survive  is  due  to  the  unceasing  efforts  of  a  few  earnest 
workers  who  saw  its  promising  future,  and  by  careful  study,  step 
by  step,  traced  failures  to  their  source,  and  unraveled  the  principles 
involved  in  designing  and  constructing  successful,  lasting  and 
asceptic,  crown  and  bridge-work.  Though  the  ideal  has  not  been 
reached,  crown  and  bridge-work  has  been  placed  upon  a  more 
secure  foundation,  and  a  most  promising  future  is  unfolded  as  the 
result  of  these  labors. 

That  the  crown  and  bridge-work  of  the  early  days  was  faulty 
was  not  due  entirely  to  poor  workmanship.  Many  of  the  early 
practitioners  were  especially  skilful  workmen,  and  did  excellent 
work.  The  trouble  lay  in  the  science  not  being  sufficiently  developed 
to  enable  them  to  work  understandingly,  especially  in  the  pre- 
paratory work  upon  which  so  much  depends.  Treatment  of  patho- 
logical conditions  was  not  understood  and  appreciated  as  it  is  now. 
Remedial  agents  and  procedures,  now  considered  indispensable, 
were  then  unknown;  instruments,  appliances  and  precautionary 
measures,  which  have  aided  so  much  to  make  this  work  effective, 
were  then  undreamed  of. 

Recognition  of  the  underlying  principles  or  factors  which  make 
for  or  against  successful  bridge-work  came  slowly.  Prominent 
among  these  was  root  and  abutment  preparation.  In  a  majority 
of  the  early  cases,  we  might  perhaps  say  in  all,  there  was  no 
attempt  made  to  prepare  the  mouth,  scientifically,  for  the  reception 
of  the  work.  The  importance  of  pulp  canal  cleansing,  thorough 
treatment  of  pathological  conditions,  and  effective  pulp-canal  filling 
was  appreciated  by  a  few  only,  and  these  were  hampered  by  de- 
fective instruments  and  inability  to  promptly  verify  the  accuracy 
of  their  work.  This  handicap  has  since  been  razed  by  the  intro- 
duction of  delicate  pulp-canal  instruments  and  the  marvelous 
x-ray. 

Abutment  trimming,  so  important  to  properly  fitting  abutment 
crowns,  was  often  ignored;  indeed,  until  the  introduction  of  prop- 
erly shaped  abrasive  wheels  and  disks,  it  was  practically  impossible. 
The  introduction  of  these  useful  instruments  was  a  step  only,  for 
until  it  was  demonstrated  that  a  devitalized  tooth  made  as  good,  or 
even  a  better  abutment  than  a  vital  tooth,  the  intense  pain  attend- 
ing abutment  trimming  too  frequently  halted  the  operation  before 
it  was  complete.  The  discovery  of  pressure  anesthesia,  and  other 
anesthetic  processes,  making  possible  the  painless  devitalizing  of  a 
pulp  without  injury  to  the  tissues  around  the  apex  of  the  tooth. 


INTRODUCTION  xi 

was  the  last  step  that  made  possible  scientific  abutment  trimming, 
and  the  construction  of  an  aceptic  abutment  crown. 

Still  another  fundamental  to  crown  and  bridge-work  success  was 
brought  to  the  fore  when  a  few  scientifically  inclined  earnest  workers, 
in  an  eftort  to  make  more  effective  artificial  dentures,  began  a 
careful  study  of  the  various  movements  of  the  mandible  during 
mastication.  The  object  of  these  eft'orts  was  to  devise  a  contrivance 
to  accurately  reproduce  these  movements  so  as  to  enable  the  dental 
workman,  when  mounting  artificial  teeth,  to  secure  a  more  normal 
occlusion. 

Heretofore,  if  the  upper  and  lower  teeth  articulated  with  each 
other  when  the  mandible  was  at  rest,  the  work  was  deemed  satis- 
factory, notwithstanding  that  the  dentures  were  quite  ineffective 
in  mastication,  t)wing  to  the  fact  that  all  the  teeth  met  only  when 
the  mandible  was  in  the  rest  position.  At  other  times  but  few  teeth 
were  in  contact.  The  immediate  result  of  these  investigations 
was  a  better  understanding  of  the  mechanism  of  mastication,  and 
a  higher  appreciation  of  the  importance  of  normal  occlusion  that 
has  since  reached  all  departments  of  our  profession.  By  occlusion 
is  understood  a  rubbing  or  grinding  surface  contact  of  all  the 
masticating  surfaces  of  the  teeth,  during  all  the  movements  of 
the  mandible,  as  is  always  the  case  with  the  natural  teeth  in 
their  normal  position.  Articulation  is  a  mere  fitting  together  in 
one  position  only. 

This  understanding  of  occlusion  brought  to  the  fore  an  imper- 
fectly recognized  cause  of  failure  of  many  dental  bridges.  With 
the  mouth  closed,  the  teeth  on  these  bridges  fitted  the  o})posing 
teeth  accurately,  but  during  mastication  they  touched  at  a  few 
points  only.  Except  for  this  fact  these  bridges  might  have  given 
many  years  of  excellent  service,  but  owing  to  defective  occlusion 
the  force  of  mastication  was  concentrated  upon  a  few  teeth,  which 
resulted  in  literally  pounding  the  structure  to  pieces  in  a  .short 
time.  In  other  cases  the  stress  set  up  a  destructive  irritation  in 
one  or  more  of  the  supporting  abutments,  which  just  as  surely 
resulted  in  the  bridge  failing. 

We  now  know  that  it  is  impossible  for  any  one  tooth  to  be  niuhilx' 
strained  during  mastication,  or  other  movements  of  the  mandible 
if  the  occlusion  of  the  denture  has  been  properly  adjusted,  be  it 
a  j^late,  a  rrowii,  or  a  bri<lgc. 

('rr)Wiiiiig  (»r  \ital  tcctli  |)n)\<'(l  to  be  the  cause  of  iiiiiiicnuis 
failures,  although  at  one  time  a  \ital  abutment  was  (Iccnicd  more 


xii  INTRODUCTION 

reliable  than  one  devitalized.  After  a  few  years  many  cases,  where 
vital  abutments  were  used,  developed  dento-alveolar  abscesses,  the 
pulp  in  the  meantime  having  died  as  the  result  of  irritation,  per- 
haps from  denuding  of  its  enamel  when  preparing  the  crown  for  an 
abutment  cap,  or  perhaps  from  irritation  due  to  the  cement.  In 
other  cases  an  overstimulation  of  the  pulp  produced  secondary 
dentin  deposits,  pulp  stones,  and  other  kindred  troubles. 

It  was  quite  a  step  forward  when  the  profession  recognized  that 
the  pulp  was  a  formative  organ,  and  that  when  its  work  was  done, 
it  was  no  longer  necessary  to  the  life  and  health  of  the  tooth. 
Also  when  a  technic  was  developed  by  which  the  pulp  could  be 
removed  painlessly  and  its  place  occupied  by  an  inert  substance, 
with  but  little  risk,  if  any,  that  the  tooth  would  ever  become  a 
source  of  trouble  as  the  result  of  its  devitalization. 

Until  within  recent  years  but  little  thought  has  been  given  to  the 
stress  of  mastication,  the  force  developed  by  the  muscles  moving 
the  mandible,  and  the  force  required  to  properly  perform  the 
function  of  mastication.  Until  this  information'  was  available, 
designing  a  bridge  to  withstand  this  force  year  after  year  was  mere 
guess-work.  Too  often  the  stress  of  mastication  and  the  strength 
of  the  bridge  or  its  abutments  was  grossly  underestimated,  and 
failures  thereby  invited.  We  now  know  that  ample  strength  must 
be  provided,  and  we  know  also,  approximately,  the  relative  strength 
or  carrying  capacity  of  the  different  teeth  when  used  as  abutments. 
This  is  another  forward  step,  and  an  important  one. 

There  is  still  another  point,  recently  impressively  brought 
to  the  fore,  and  a  very  important  point  it  is.  A  very  serious  charge 
has  been  brought  against  crown  and  bridge-work  by  our  medical 
brethren.  They  claim  that  as  generally  designed  and  constructed, 
crown  and  bridge-work  is  often  a  serious  menace  to  the  patient's 
health.  That  many  serious  ailments  have  been  caused  and  main- 
tained by  septic  conditions  associated  with  crown  and  bridge-work 
often  worn  by  the  patient  with  great  comfort  and  satisfaction.  The 
proof  presented  is  so  strong  and' convincing  as  to  challenge  inves- 
tigation, and  prompts  the  question,  Why? 

This  brief  resume  of  the  progressive  development  of  crown  and 
bridge-w^ork  will  no  doubt  have  suggested  to  the  thoughtful  reader 
the  answer  to  this  important  question,  and  may,  perhaps,  have 
suggested  another.  Why  was  not  this  discovered  earlier,  when  the 
art  was  crude,  and  the  work  in  all  its  phases  more  imperfectlj'^  done? 

IMedical  science  has  made  a  marvelous  advance  during  recent 


IXTliODLCTWX  Nlil 

years  in  tracing  pathological  lesions  to  their  causes.  Man>'  dis- 
orders that  were  formerly  treated  with  indifferent  success,  by 
methods  suggested  by  the  symptoms  developed,  are  now  recognized 
as  pathological  conditions  due  to  remote  causes,  causes  at  times 
located  far  from  the  seat  of  trouble,  and  seemingly  to  the  un- 
scientific observer,  having  no  connection  whatever  with  it.  The 
cause  recognized  and  removed,  the  disease  is  cured. 

This  has  been  the  case  in  many  instances  to  wearers  of  crown 
and  bridge-work.  They  have  suffered,  in  some  cases  for  years,  with 
but  little  relief  until  the  medical  attendant  was  led  to  suspect 
that  septic  infection  was  the  real  cause.  A  careful,  step-by-step 
diagnosis  by  exclusion  has  located  this  in  a  highly  priced  piece  of 
bridge-work,  a  masterpiece  of  prosthetic  dentistry.  Its  removal 
has  disclosed  a  horrible  condition  of  affairs.  A  judicious  use  of 
the  forceps  and  oral  prophylaxis,  followed  })y  a  rapid  cure,  proved 
the  diagnosis  correct. 

In  order  to  purge  crown  and  bridge-work  of  any  possible  stigma 
now  resting  upon  it,  our  profession  must  make  practical  use  of  the 
knowledge  gained  by  experience,  and  that  furnished  by  the  research 
and  observations  of  our  medical  brethren.  Xo  half-way  measures 
will  suffice.  It  must  be  made  aseptic  from  the  foundations  up. 
All  pathological  conditions  must  be  thoroughly  and  radically 
treated,  and  the  treatment  continued  until  a  cure  is  effected  and 
all    sources   of   septic   invasion   remo\ed. 

In  comparing  the  general  output  of  crown  and  bridge-work  as 
we  see  it  today  with  tliat  of  the  pa.st,  there  is  not  that  marked 
difference  in  its  diaracter  we  have  a  right  to  expect,  considering 
the  tremendous  advances  which  have  been  made  in  our  knowledge 
of  the  physiology  and  pathology  of  the  dental  pulp,  and  the  technic 
of  root  and  pulp-canal  treatment.  This  is  really  where  the  trouble 
is.  This  knowledge  has  not  l)een  utilized  as  it  should  have  been 
in  making  crown  and  bridge-work  better  and  safer. 

Modern  methods  of  treating  such  i)athological  conditions  as 
lia\e  been  resj)onsible  for  the  undoing  of  crown  and  i)ridge-work 
are  radical,  and  radically  different  from  those  which  liaxc  prevailed 
in  the  past.  I'ul))  and  pul|)-canal  treatment  as  it  should  be  done 
when  prei)aring  lor  cnnvn  and  bridge-work  is  tedi()us,  it  takes  time, 
it  requires  patience  and  exacting  care  to  make  sure  that  it  is  well 
done.  The  mechanical  i)reparatioti  of  roots  and  abutmeiit  teeth,  as 
we  now  know  the.\-  must  be  prepared,  is  \-er\  different  from  the 
slijjshod  methods  of  the  past.      It  is  regrettable  that  these  matters 


xiv  INTRODUCTION 

have  not  been  generally  realized.  Had  this  specialty  correspond- 
ingly developed  with  the  development  of  our  knowledge  of  the 
various  technical  procedures  underlying  the  scientific  construction 
of  bridge-work,  we  should  have  so  improved  the  character  and 
efficiency  of  the  average  output  of  bridge-work,  as  to  have  made  it 
beyond  all  comparison  better  than  the  bridge-work  of  the  past. 

In  order  that  these  results  may  yet  be  accomplished  by  the  means 
already  at  our  command,  it  is  necessary  that  we  give  earnest  atten- 
tion to,  not  only  the  underlying  principles  upon  which  all  good 
bridge-work  is  founded,  but  also  sympathetic  and  careful  attention 
to  the  infinite  number  of  minor  as  well  as  major  details,  both 
technical  and  artistic,  which  are  collectively  necessary  to  the 
attainment  of  excellence  in  this  and  in  all  things  which  are  worth 
doing  well. 


CROAVN  AND  BRIDGE-WORK. 


CHAPTER   1. 
ARTIFICIAL  CROWNS. 

When  the  natural  crown  of  a  tooth  lias  become  broken  down 
or  decayed  to  such  an  extent  that  it  is  impracticable  to  restore 
it  by  means  of  fillings  or  inlays  it  becomes  necessary  to  resort  to 
some  other  means  of  restoration  to  enable  it  to  perform  its  normal 
function.    This  is  done  by  means  of  an  artificial  crown. 

There  are  three  types  of  crowns  which  are  used  for  this  purpose, 
dift'ering  from  each  other  chiefly  in  the  manner  of  their  retention, 
the  first  type  being  retained  in  position  by  means  of  a  pin  or  post 
inserted  into  the  enlarged  pulp  canal.  The  second  is  hel  I  in  place 
by  means  of  a  collar  or  band  which  encircles  the  stump  of  the  tooth. 
The  third  is  a  combination  of  these  two,  having  both  a  band  and 
post  to  give  the  necessary  support. 

The  first  of  these  is  used  almost  exclusively  in  the  teeth  anterior 
to  the  molars.  The  second  is  confined  almost  wholl>'  to  the  molars 
but  at  times  is  used  as  far  forward  as  the  bicuspids  and  under  cer- 
tain conditions  for  the  anterior  teeth.  The  third  is  used  principally 
in  the  anterior  teeth,  but  is  also  at  times  indicated  in  the  posterior 
teeth. 


Fiu.  1 


There  are  two  classes  of  this  first  type  of  crown;  one  being  that 
in  which  the  post  is  an  integral  part  of  the  crown  itself,  being  baked 
into  the  porcelain  or  soldered  to  it  fl''ig.  I  j.     In  the  first  class  we 
2 


18  ARTIFICIAL  CROWNS 

have  the  Logan  crowns  and  the  pin  and  post  crowns.  The  second 
class  is  one  in  which  the  crown  and  post  are  separate,  there  being 
an  opening  in  the  base  of  the  crown  or  entirely  through  it  in 
which  the  post  is  cemented  or  otherwise  fixed  (Figs.  2  and  3). 


Fig.  3 


Examples  of  this  class  may  be  found  in  the  Bonwill  crowns, 
Davis  crowns,  Justi  crowns,  and  the  English  tube  teeth. 

There  is  little  choice  between  the  different  crowns  of  these  types. 
That  which  best  meets  the  requirements  of  a  given  case  in  mold, 
shade  and  texture  may  be  chosen. 

There  are  also  two  classes  of  the  second  type  of  crown.  The 
first  is  used  exclusively  in  the  back  of  the  mouth,  being  made 
entirely  of  metal  and  is  represented  by  the  gold  shell  crown.  The 
second  class  is  a  combination  of  both  metal  and  porcelain,  having 
a  band  for  retention,  but  the  exposed  portions,  the  face  or  occlu- 
sal surfaces  being  covered  with  veneers  or  porcelain.  An  example 
of  this  class  may  be  seen  in  the  jacket  crown. 

In  the  third  type  we  have  the  so-called  Richmond  crown,  or  a 
crown  with  a  Richmond  base  and  an  all  porcelain  crown  attached 
to  it. 

These  different  types  of  crowns  are  used  as  single  crowns,  or  as 
abutment  crowns,  or  dummies  in  bridge-work. 

ESSENTIALS  TO  SATISFACTORY  BRIDGE-WORK. 

General  Considerations. — When  consulted  regarding  the  advisa- 
bility of  inserting  a  piece  of  bridge-work,  there  are  three  funda- 
mental factors  to  be  considered:  the  number,  position,  and  con- 
dition, of  teeth  or  roots  available  as  abutments.  The  whole  story 
of  requirements  for  this  work  may  be  summed  up  in  these  three 
words.  If  the  available  teeth  or  roots  are  lacking  in  number,  or 
are  unsatisfactory  as  to  position  or  condition,  an  essential  to  success 
is  wanting,  and  the  work  is  contra-indicated. 

There  are  certain  mechanical  and  scientific  principles  governing 
this  work  and  these  same  principles  are  involved  whether  we  are 
placing  a  bridge  in  the  mouth  or  across  a  river.     There  must  be 


ESSENTIALS  TO  SATISFACTORY  BRIDGE-WORK  19 

sufficient  number  of  abutments  to  carry  the  weight  which  will  be 
imposed  upon  it,  and  their  position  and  condition  must  be  such  as 
to  give  stability  to  the  structure,  and  to  withstand  any  strain  to 
which  it  may  l)e  subjected,  otherwise  it  will  collapse. 

Partial  Plates  vs.  Bridge-work. — In  a  very  large  percentage, 
probably  in  the  majority  of  mouths  where  partial  plates  are  now 
worn,  bridge-work  could  be  used  to  much  better  advantage,  and 
would  be  far  more  serviceable  than  are  the  plates.  Partial  plates 
are  always  decidedly  objectionable  and  are  to  be  avoided  if  possible. 
The  plates,  almost  invariably  injure  the  soft  tissues  and  the  ad- 
joining teeth,  the  pressure  gradually  forcing  the  gum  away  from  the 
necks  of  the  teeth,  which  are  abraded  by  the  constant  movement 
of  the  plate,  and  in  many  instances  this  results  in  their  loss.  This  is 
especially  true  where  the  plate  is  of  small  dimensions,  carrying 
but  one  or  two  teeth. 

In  every  case,  or  at  least  all  but  the  simplest,  it  is  best  to  take 
plaster  impressions  of  the  mouth  and  make  accurately  articulated 
models,  trimmed  so  that  they  may  be  examined  from  every  point 
of  view,  both  from  the  inside  as  well  as  the  outside.  These  models 
shoulfl  be  studied  carefully  before  deciding  on  any  definite  line  of 
operation. 

The  number,  position,  and  general  condition  of  the  teeth  being 
satisfactory,  the  success  of  a  crown,  or  of  a  bridge,  depends  en- 
tirely upon  the  preparation  of  the  teeth,  or  roots,  which  are  to 
serve  as  abutments.  By  this  preparation  is  meant  not  simply  the 
mechanical  trimming  of  the  teeth  or  roots  for  the  reception  of  the 
bands  or  posts,  but  it  begins  at  the  beginning  with  the  treatment 
of  any  pathological  conditions  which  may  be  present,  the  dexital- 
izing  and  removal  of  the  pulp,  and  the  sterilizing  and  filling  of 
the  canals.     This  will  be  considered  in  the  succeeding  chapter. 

The  accompanying  illustrations  (pages  20  and  21)  are  accurate 
reproductions  from  Traite  de  la  Partie  Mecanique  de  Fart  du 
Chirurgien-Dcnfis-fc,  par  (\  F.  I)elal)arre,  i)ublished  in  1S2().  They 
give  a  ver\'  good  idea  of  the  crown  work  which  was  done  at  that 
time. 

We  are  cnablcl  to  reproduce  these  figures  through  the  kindness 
of  Dr.  K.  J.  Uanhofer,  of  New  York. 


20 


ARTIFICIAL  CROWNS 


ESSENTIALS  TO  SATISFACTORY  BRIDGE-WORK  21 


A 


0/1 


CHAPTER  II. 

PATHOLOGICAL  CONDITIONS  IN  THEIR  RELATION 
TO  CROWN  AND  BRIDGE-WORK. 

It  is  not  the  intention  of  the  writer  to  consider  the  treatment  of 
pathological  conditions  except  as  they  are  directly  related  to 
crown  and  bridge-work.  Inasmuch,  however,  as  a  healthy  condition 
of  the  teeth  and  roots  utilized  as  supports  for  crowns  and  bridges 
is  a  fundamental  to  success,  pathological  conditions  of  the  teeth 
and  their  treatment,  is  of  the  utmost  importance  to  crown  and 
bridge-workers. 

Each  factor  making  for  success  or  failure  must  be  carefully 
considered,  and  nothing  left  to  chance.  Loose  teeth  need  not 
necessarily  preclude  the  idea  of  inserting  a  bridge;  they  should  be 
carefully  studied  in  order  to  determine  the  cause,  and  whether  or  not 
they  can,  by  thorough  treatment,  be  brought  to  a  normal,  healthy 
condition.  If  this  is  impossible,  then,  of  course,  unless  other  teeth 
are  available,  a  crown  or  bridge  is  not  to  be  thought  of. 

Loose  Teeth. — Looseness  of  teeth  may  be  brought  about  by  many 
causes,  such  as  pyorrhea  alveolaris,  dento-alveolar  abscess,  kidney 
troubles,  malocclusion  or  want  of  occlusion,  etc.  Some  of  these 
causes  may  require  the  services  of  a  physician,  those  due  to  faults 
of  occlusion,  and  many  others,  will  usually  yield  to  thorough  dental 
treatment.  Nothing  should  be  done,  however,  until  the  cure  is 
effected  and  the  teeth  have  become  firm. 

Pyorrhea  Alveolaris. — A  case  of  pyorrhea,  if  it  be  serious,  is  gener- 
ally better  referred  to  a  specialist,  as  one  specializing  in  this  par- 
ticular branch,  will  probably  get  better  results  than  another  who 
treats  it  only  occasionally. 

In  its  earlier  stages  a  cure  may  be  effected  by  thorough  in- 
strumentation, and  cleansing  the  parts  affected  with  antiseptic 
solutions.  The  affected  teeth,  when  the  disease  is  well  advanced, 
are  generally  useless  as  supports  for  crowns  or  bridges. 

Pyorrheal  Conditions. — Conditions  are  frequently  met  with  in  the 
oral  cavity  resembling  pyorrhea  which  are  not  really  this  disease. 


PUTRESCENT  PULP  CANALS  23 

They  may  l)e  caused  by  some  Icx-al  irritation,  such  as  Ugatures 
forgotten,  and  left  around  a  tooth,  below  the  gum  margin,  causing 
irritation  resulting  in  infection,  and  a  flow  of  pus.  The  same  effect 
may  be  brought  about  by  a  splinter,  as  from  a  tooth  pick,  or 
some  such  like  irritation.  These  cases  may,  at  first  sight,  be 
mistaken  for  pyorrhea.  The  removal  of  the  cause  usually  effects 
a  cure. 

Putrescent  Pulp  Canals. — In  treating  a  putrescent  pulp  canal  the 
first  stej)  is  to  cleanse  it  mechanically,  as  thoroughly  as  possible. 
The  greatest  care  must  be  exercised  in  doing  this  so  as  not  to  force 
any  of  the  putrescent  matter  or  gas  through  the  apical  foramen. 
The  instruments  best  suited  for  this  purpose  are  the  Donaldson 
canal  cleansers.  These  instruments  are  barbed  in  such  a  manner 
that  the  barbs  follow  around  the  shaft  in  the  same  manner  as 
does  the  thread  on  a  right-hand  screw,  so  that  by  rotating  the 
instrument  is  drawn  into  the  canal  without  the  necessity  of  using 
the  slightest  force. 

The  instrument  is  dipped  in  carbolic  acid  or  other  strong  anti- 
septic, the  point  placed  in  the  canal  and  the  instrument  turned 
slowly  to  the  right.  As  it  is  carrierl  into  tlic  canal  it  is  frequently 
withdrawn  and  cleansed  of  the  matter  adhering  to  it,  until  the 
vicious  matter  is  entirely  removed.  By  working  in  this  manner  there 
is  no  danger  of  carrying  any  of  the  putrescent  mass  through  the 
end  of  the  root.  It  is  of  the  greatest  importance  that  not  the 
slightest  force  be  used  on  the  instrument.  After  the  bulk  of  the 
softened  mass  is  removed,  the  sides  of  the  canal  are  scraped  with 
the  same  instrument,  until  it  is  fairly  well  cleansed. 

Sodium  and  potassium,  or  sodium  dioxide,  is  then  used,  being 
carried  into  the  canal  with  a  fine  instrument,  })urning  out  any  of  the 
disintegrated  pulp  tissue  which  remains  in  the  root.  This  should 
be  done  thoroughly,  and  a  little  of  the  sodium  and  potassium 
left  in  the  canal  until  a  subseciuent  sitting.  When  the  patient 
returns,  the  treatment  with  the  sodium  and  potassium  is  repeated, 
after  which  the  canal  should  be  washed  out  with  a  solution  of 
bichloride  of  rnercnry  and  jxToxide  of  hydrogen,  "^riie  caiiid  is  then 
thoroughly  flrierl  and  filled. 

In  the  absence  of  the  sodium  and  potassium,  or  sodium  dioxide, 
formalin  may  be  used,  but  this  should  not  be  sealed  in  the  root, 
unless  the  foramen  is  closed,  or  is  very  minute,  as  it  is  an  active 
irritant  and  may  cause  consideral)]e  pain  and  trouble. 


24  PATHOLOGICAL  CONDITIONS 

Sterilizing  a  Pulp  Canal  with  Formalin. — In  sterilizing  a  pulp  canal 
with  formalin,  the  following  method  will  prove  effective.  After 
the  root  has  been  as  thoroughly  cleansed  mechanically  as  is  possible 
under  the  existing  conditions,  it  is  dried  with  alcohol  and  the  canal 
wiped  out  with  a  strong  solution  of  formalin,  running  from  10  to 
40  per  cent,  the  full  strength  of  the  solution,  using  a  wisp  of  cotton 
twisted  around  a  broach  as  a  carrier.  It  is  then  dried  with  hot 
air  or  a  heated  root-drier,  thereby  driving  the  formalin  into  the 
tooth  structure.  This  operation  is  repeated  a  number  of  times  until 
it  is  certain  that  the  root  has  been  thoroughly  sterilized,  after  which 
it  may  be  filled. 

Where  there  has  been  a  slight  irritation  in  the  apical  region,  it  is 
a  good  plan  to  enlarge  the  foramen  very  slightly  before  treating, 
and  a  dressing  of  tricresol  and  formalin  may  be  sealed  in  the  canal 
and  left  for  a  day  or  two,  to  be  repeated  if  necessary. 

Where  there  has  been  an  excessive  and  continued  irritation,  it  is 
best  to  treat  the  case  in  a  thorough  manner,  opening  through  the 
process  to  the  apex,  giving  it  the  same  treatment  indeed,  as  in  the 
case  of  a  dento-alveolar  abscess,  and  then  filling  the  root  at  once. 

When  on  opening  into  a  tooth,  if  the  pulp  is  dried  up  and  in  a 
mummified  condition,  the  canal  should  be  given  the  same  treatment 
and  care  as  though  the  pulp  was  putrescent. 

The  same  treatment  should  be  employed  in  the  case  of  cotton 
filled  roots,  which  are  sometimes  met  with,  without  regard  to  the 
condition  they  may  seem  to  be  in,  foul  or  sweet.  In  a  major- 
ity of  these  cases  the  canals  are  in  a  putrid  condition,  and  before 
being  utilized  they  should  be  treated  as  advised  for  the  canals  of 
putrescent  pulps. 

PULP  INFECTION  AND  TREATMENT  OF  RESULTANT 
CONDITIONS. 

There  are  many  causes  which  may  bring  about  the  death  of  the 
pulp  and  unless  this  condition  is  recognized  very  early  and  properly 
treated,  trouble  of  a  more  or  less  serious  nature  is  liable  to  follow. 

There  are  cases  where  the  pulp  has  become  devitalized  and  re- 
mained quiescent  for  a  number  of  years,  the  patient  being  unaware 
that  there  is  anything  wTong  with  the  tooth,  but  this  is  not  of 
frequent  occurrence;  more  frequently  the  trouble  becomes  manifest 
within   a  comparatively   short  time. 

With  the  infection  and  decomposition  of  the   pulp  tissue,  the 


PULP  INFECTION  AND  TREATMENT 


25 


danger  begins.  A  minute  portion  of  this  putrescent  matter,  or  a 
little  of  the  gas  generated  by  it,  finding  its  way  through  the  apical 
foramen  will  set  up  an  irritation  and  inflammation;  infection  follows, 
resulting  in  the  formation  of  a  dento-alveolar  abscess.  This  condition 
is  too  often  lightly  considered,  and  an  abscessed  tooth  looked  upon 
as  of  minor  importance,  when  in  reality  it  is  a  grave  condition  and 
may  cause  serious  pathological  disturbances,  and  not  infrequently 
death  has  followed  from  septicemia  caused  by  resorption  of  pus. 

Dento-alveolar  Abscess. — This  is  one  of  the  troubles  with  which 
the  crown  and  bridge  specialist  is  most  frequently  confronted. 
As  a  general  thing,  it  is  also  one  of  the  easiest  to  cure. 

In  this  as  in  every  step  in  crown  and  bridge-work,  thoroughness 
is  necessary  to  success,  and  unless  one  is  willing  to  give  the  time 
and  attention  necessary  to  effect 
a  cure,  it  is  far  better   not  to 
attempt  its  treatment. 

With  the  formation  of  pus 
around  the  apex  of  the  root,  there 
is  a  destruction  of  tissue  extend- 
ing in  all  directions,  thus  form- 
ing an  irregular  cavity  or  sac 
into  which  the  apex  of  the  root 
extends  (Fig.  4). 

As  the  amount  of  pus  increases, 
it  will   gradually  force   its  way 

through  the  alveolar  process  and  gum  tissue,  thus  establishing  a 
fistula. 

If  there  is  a  cavity  in  the  tooth  through  which  the  pus,  after 
passing  through  the  canal,  may  be  discharged  into  the  mouth, 
there  will  be  no  external  fistula;  this  is  termed  a  blind  abscess. 

The  treatment  of  an  abscess  which  has  no  outlet  for  the  pus 
excepting  that  through  the  root  of  the  tooth,  should  never  be 
undertaken.  It  is  practically  impossible  to  force  the  remedies 
through  the  apical  foramen  into  the  pocket  or  sac  of  the  abscess, 
or  to  cleanse  it  thoroughly  and  remove  the  debris  without  having 
an  external  fistula.  Treatment  through  the  root  may  relieve  the 
trouble  temporarily,  but  it  is  liable  to  recur  at  any  time. 

In  the  case  of  an  acute  dento-alveolar  abscess,  where  there  is  a 
fistula  established,  a  cure  can  generally  be  eU'ected  c|uickly  and 
easily.  It  is  not  necessary  to  have  the  patient  make  daily  visits, 
as  with  proj)(T  care  it  is  xcry  rarely  that  it  is  necessary  to  give  it 


Fig.  4 


26  PATHOLOGICAL  CONDITIONS 

more  than  one,  or,  at  the  most,  two  treatments,  in  order  to  effect 
a  permanent  cure,  but  in  doing  this,  every  step  of  the  operation 
must  be  done  thoroughly. 

For  many  years  the  writer  has  had  almost  uninterrupted  success 
in  the  treatment  of  this  trouble  by  using  the  following  method : 

The  canal  is  first  cleansed  as  thoroughly  as  possible  mechanically, 
using  Donaldson's  canal  cleansers,  or  instruments  of  that  type, 
and  scraping  the  sides  of  the  canal  thoroughly  so  as  to  remove  every 
particle  of  diseased  tissue  which  can  be  reached. 


Fig.  5. — Bulb  syringe. 

It  should  then  be  ascertained  beyond  doubt  that  there  is  an 
open  fistula,  through  which  the  remedies  will  readily  flow,  and  this 
can  be  done  by  using  distilled  water  or  a  mild  antiseptic  solution, 
after  which  the  first  agent  used  is  hydrogen  peroxide. 

Objections  have  been  strongly  urged  against  the  use  of  this  agent, 
the  claim  being  much  that  it  will  cause  necrosis  and  sloughing,  but 
during  the  experience  of  twenty-five  years,  the  writer  has  not  had  a 
single  case  where  this  has  occurred.  If  the  peroxide  were  forced  into 
a  closed  sac  under  pressure,  then  serious  trouble  might  ensue,  but 
where  there  is  a  free  vent  there  is,  practically,  no  danger  from  its  use. 

Treatment  of  Acute  Dento-alveolar  Abscess. — In  the  treatment 
of  acute  dento-alveolar  abscess  it  is  necessary  that  suitable  in- 
strument for  injecting  the  remedies  be  used.  A  rubber  bulb  syringe, 
with  platinum  point,  known  as  an  abscess  syringe  is  most  useful 
for  this  purpose  (Fig.  5).  The  capacity  of  the  bulb  of  this  syringe 
is  one-quarter  of  an  ounce. 

In  order  to  insure  the  remedy  being  forced  through 

(^S^^^^    the  canal  and  out  through  the  fistula,  it  is  necessary 

to  use  a  packing,  preferably  of  rubber.     This  is  very 

easily  made  by  forcing  the  needle  through  a  piece 

of  heavy  separating  rubber,  of  sufficient  size  to  entirely  cover  the 

opening  in  the  tooth  or  root,  letting  the  end  of  the  needle  extend 

a  little  beyond  this  rubber  packing,   as  in  Fig.   6. 


PULP  INFECTION  AND  TREATMENT  27 

The  point  is  then  introduced  into  the  opening  in  the  canal  or 
tooth  and  the  rubber  pressed  tightly  over  the  opening  and  around 
the  needle  with  a  pair  of  cotton-pliers.  This  will  efFectually  prevent 
the  fluid  from  escaping  at  this  point,  and  will  insure  its  reaching 
the  place  where  it  is  needed. 

The  abscess  is  first  washed  out  with  sterile  water  so  as  to  ascertain 
that  there  is  a  free  vent,  then  hydrogen  peroxide  is  forced  very 
slowly  through  the  root  and  out  of  the  fistula,  and  this  is  continued 
as  long  as  there  is  any  eftervescence.  It  is  sometimes  necessary 
to  use  a  large  amount  of  the  peroxide  before  the  pocket  is  entirely 
cleansed.  At  times  one  or  two  ounces  or  even  more  may  be  required, 
but  it  should  be  continued  until  the  solution  comes  through  perfectly 
clear. 

The  hydrogen  peroxide  is  followed  by  the  standard  solution  of 
aromatic  sulphuric  acid.  This  solution  is  used  in  its  full  strength 
as  given  in  the  United  States  Pharmacopeia  and  contains  about 
10  per  cent,  by  bulk,  or  20  per  cent,  by  weight,  of  sulphuric 
acid. 

The  amoiuit  of  the  aromatic  sulphuric  acid  used  is  from  one- 
quarter  to  one-half  of  a  syringeful,  or  from  one-sixteenth  to  one- 
eighth  of  an  ounce,  or  at  times  even  more  than  this. 

The  point  of  the  syringe  is  inserted  into  the  canal  and  the  rubber 
packing  pressed  tightly  against  the  tooth,  as  with  the  hydrogen 
peroxide,  and  the  acid  forced  through  very  slowly.  This  heljrs  to 
destroy  any  remaining  diseased  tissue  and  acts  as  a  stimidant. 
The  acid  should  be  met,  as  it  comes  through  the  fistula  with  a 
syringe  full  of  a  saturated  solution  of  bicarbonate  of  soda,  so  as 
to  counteract,  or  neutralize,  the  action  of  the  acid  before  it  comes 
in  contact  with  the  teeth  and  the  soft  tissues  of  the  mouth.  The 
bicarbonate  of  soda  should  be  used  freely,  as  much  as  three  or 
four  syringe  fulls  during  the  injection  of  the  acid,  and  afterward 
the  mouth  should  be  rinsed  freely  with  the  same. 

After  the  acid  has  been  used,  the  root  should  be  filled  at  once. 
If  it  is  left  open  for  any  length  of  time,  infection  may  recur,  and  it 
will  be  necessary  to  repeat  the  operation  as  there  is  a  serious  risk 
of  reinfection  as  long  as  the  root  remains  open. 

After  treating  an  abscess  in  this  manner  and  filling  the  root  canal, 
it  will  generally  recpure  from  ten  days  to  two  or  even  three  weeks 
before  the  parts  are  finally  healed.  During  this  time  there  will  be  a 
discharge  of  blood  and  serum  through  the  fistula,  presenting  the 
aj)pearance  of  pns,  but  this  is  a  perfectly  nalnral  condition,  as  there 


28 


PATHOLOGICAL  CONDITIONS 


is  a  normal  sloughing  of  the  disintegrated  tissues  which  must  be 
expelled  as  the  parts  are  healing. 

At  times,  when  the  edges  of  the  wound  are  fresh,  the  fistula 
may  close  up  at  once,  or  within  two  or  three  days,  but  it  will  break 
out  again,  and  this  may  be  repeated  several  times;  it  will  not  heal 
finally  until  all  of  the  sloughed  tissue  has  entirely  disappeared  and 
healthy  granulations  have  replaced  it. 

It  is  very  rarely,  in  the  case  of  an  acute  abscess,  that  it  is  necessary 
to  repeat  this  treatment,  but  it  should  be  remembered  that  the 
cure  depends  entirely  upon  the  thoroughness  with  which  the 
operation  has  been  performed. 

Establishing  a  Fistula.- — If  there  is  no  external  opening,  and  the 
abscess  has  been  draining  through  the  pulp  canal  of  the  tooth,  it  is 
necessary  to  establish  a  fistula.  Occasionally,  by  sealing  the 
opening  through  the  tooth  for  a  time,  nature  will  establish  one  with 
comparatively  little  discomfort  to  the  patient,  but  if  this  cannot 
be  done,  it  becomes  necessary  to  make  an 
opening  through  the  gum  and  process. 

A  spear-pointed  drill  is  best  suited  for  this 
purpose;  it  should  be  of  a  large  size,  sharp, 
and  perfectly  sterilized. 

Locating  the  Apex  of  the  Root.: — It  is  neces- 
sary to  first  locate  the  apex  so  as  to  know 
exactly  where  to  drill.  The  foramen  is  slightly 
enlarged  in  order  to  ascertain  the  exact  length 
of  the  tooth  or  root.  This  can  be  done  with 
a  small  hooked  broach,  passing  it  through  the 
canal  and  catching  the  hook  over  the  end  of  the 
root.  A  small  piece  of  rubber  dam  is  pressed 
down  over  the  broach  to  the  incisal  edge  of  the 
tooth  or  against  the  end  of  the  root  (Fig.  7). 
The  broach  is  then  removed.  The  position  of 
the  rubber  indicates  the  exact  distance  from  the 
end  of  the  root  or  the  incisal  edge  of  the  tooth  to 
the  apex.  A  perfectly  straight  broach  is  then  in- 
serted, being  of  a  larger  size  than  the  one  used 
in  measuring  the  length  of  the  root,  one  that 
will  wedge  in  the  canal  with  the  end  passing 
through  the  foramen  into  the  pocket,  the  handle  extending  beyond 
the  incisal  edge  of  the  tooth,  as  in  Fig.  8,  a.  By  following  the  line 
of  this  broach  the  exact  direction  of  the  canal  is  indicated. 


Fig.  7 


PULP  INFECTION  AND  TREATMENT 


29 


By  placing  the  hooked  broach  over  the  gum  and  bringing  the 
piece  of  rubber  dam  even  with  the  incisal  edge  of  the  tooth,  or  with 
the  end  of  the  root,  it  will  show  exactly  how  far  from  the  incisal 
edge  to  drill  in  order  to  strike  the  pocket 
or  the  end  of  the  root  (Fig.  8,  b). 

Using  these  two  as  a  guide,  and  follow- 
ing the  direction  of  the  broach  which  is 
wedged  into  the  root,  the  drill  can  be 
directed  so  as  to  reach  with  certainty  the 
apex.  This  operation  can  be  quickly  and 
easily  performed  by  using  a  general  anes- 
thetic, but  it  is  very  rarely  that  a  general 
anesthetic  is  indicated,  as  the  time  re- 
quired is  so  short  that  a  local  anesthetic, 
used  hypodermically,  will  give  satisfac- 
tory results. 

Painless  Insertion  of  the  Hypodermic 
Needle. — With  patients  who  are  of  a 
highly  nervous  temperament,  or  where 
the  tissues  are  extremely  sensitive,  the 
l)ain  caused  by  the  insertion  of  the  hypo- 
dermic needle  is  at  times  almost  as  great 
as  would  be  the  pain  of  the  operation  if 
it  were  performed  without  an  anesthetic. 
The  pain  caused  by  the  forcing  of  a 
hypodermic  needle  into  the  soft  tissue 

may  be  greatly  lessened  if,  when  the  syringe  is  filled,  the  flat- 
tened side  of  the  point  of  the  needle  is  pressed  tightly  against 
the  gum  and  the  end  of  the  finger  pressed  ov(t  the  point,  at  the 
same  time  pressing  on  the  plunger.  It  is  held  thus  for  a  moment 
and  gradually  the  needle  is  forced  into  the  tissue,  the  pressure  on 
plunger  being  kept  up  all  the  time.  In  this  way  the  tissues  are 
anesthetized  in  advance  of  the  needle,  and  the  operation  rendered 
almost  painless.  The  gum  should  be  first  cleansed  and  dried  with 
alcohol  and  it  is  well  to  touch  it  with  iodine  before  attempting 
to  insert  the  needle. 

The  opening  through  the  gum  to  tlie  process  can  be  made  with  a 
lance,  a  trephine,  or  by  using  a  sharp  spoon-shaped  excavator;  with 
the  lMtt<T,  by  dipping  it  in  carbolic  acid  and  scraping  the  gum  a 
little  bit,  then  di])ping  in  the  aci<l  again  and  repeating  this  operation 
until  the  process  has  been  reached.    It  is  possible  thus  to  go  through 


Fig.  8 


30  PATHOLOGICAL  CONDITIONS 

the  tissue  to  the  process  without  drawing  blood,  and  causing  very 
little  or  no  pain  to  the  patient. 

It  is  possible  to  take  a  drill,  with  the  edges  of  the  blade  very  sharp, 
and  drill  directly  through  the  gum,  but  unless  the  edges  of  the  drill 
are  very  sharp,  there  is  danger  that  the  gum  tissue  may  be  caught, 
and  twisted  around  the  drill,  and  badly  torn.  The  use  of  the  lance 
is  the  quickest  and  easiest  method,  making  a  straight  incision 
on  a  line  with  the  long  axis  and  over  the  apex  of  the  tooth,  or,  if  it 
is  desired,  a  crucial  incision  may  be  made. 

The  point  of  the  drill  is  placed  over  the  apex  of  the  root  as  indi- 
cated by  the  broaches  which  are  serving  as  guides. 

The  engine  should  be  run  very  rapidly  and  the  aim  be  to  strike 
the  end  of  the  broach  which  is  wedged  in  the  root  canal,  at  about 
the  point  where  it  emerges  through  the  foramen. 

Some  operators,  especially  among  the  younger  practitioners,  are 
timid  and  dread  performing  an  operation  of  this  kind,  but  it  is 
.very  simple  and  is  quickly  done,  not  requiring  more  than  a  few 
seconds  at  the  most. 

As  soon  as  the  pocket  is  entered,  a  fistula  is  established  through 
which  the  remedies  can  be  forced  freely. 

Chronic  Dento-alveolar  Abscess. — When  an  abscess  has  become 
chronic,  extending  over  a  period  of  several  years,  a  necrotic  condition 
in  the  apical  region  is  established,  and  a  portion  of  the  root  will 
also  be  necrosed.  This  necrosed  area  must  be  entirely  cut  away 
and  the  diseased  portion  of  the  root  removed  in  order  to  effect  a 
cure. 

Treatment. — The  apex  is  located  in  the  manner  already  described. 
The  incision  in  the  gum  should  be  larger  than  where  simply  estab- 
lishing a  fistula.  It  should  be  at  least  one-half  inch  in  length.  A 
large  spear-pointed  drill  is  first  used  and  is  followed  by  a  large 
Coarse  rose  or  pear-shaped  bur  to  enlarge  the  opening  through 
the  process  and  bur  away  the  necrosed  bone.  The  necrosed  bone 
must  be  entirely  removed,  and  during  the  operation,  frequent 
examinations  should  be  made  with  an  explorer  or  excavator,  and  the 
burring  continued  as  long  as  there  is  the  slightest  trace  of  necrosed 
tissue.  This  can  readily  be  determined  by  the  sense  of  touch. 
The  necrosed  bone  has  a  coarse  or  honey-combed  texture,  readily 
recognized  by  the  instrument,  while  the  healthy  bone  is  smooth 
in    comparison. 

After  the  diseased  tissue  is  entirely  removed,  the  wound  is  washed 
out  with  sterile  water,  and  is  then  given  the  same  treatment  as 


PULP  INFECTION  AND  TREATMENT  31 

already  described  in  the  case  of  an  acute  abscess  using  hydrogen 
peroxide  and  aromatic  sulphuric  acid,  after  which  the  root  is  filled 
at  once. 

Amputation  of  the  Root  End  for  the  Relief  of  Dento-alveolar  Abscess. 
— In  amputating  the  apex  of  a  tooth  root,  some  operators  advise 
the  use  of  a  fissure  bur,  cutting  straight  across  the  root,  thus  re- 
moving the  end  in  one  piece. 

In  the  writer's  opinion,  this  is  an  error,  as  the  piece  is  left  in  the 
pocket  and  at  times  the  part  cut  awaA'  is  so  large  that  it  can  only  be 
removed  by  greatly  enlarging  the  opening  through  the  process.  If 
it  is  not  removed  it  will  act  as  an  irritant  and  there  will  be  a  recur- 
rence of  the  trouble. 

A  large  rose  bur  or  pear-shaped  bur  is  indicated  for  this  work, 
starting  from  the  apex  and  burring  away  the  root  gradually  as 
far  as  is  necessary,  the  root  is  thus  reduced  to  fine  particles  which 
are  easily  washed  out  from  the  pocket.  The  after-treatment  is  the 
same  as  that  for  an  acute  abscess. 

]\Iany  operators  prefer  filling  the  root  before  amputating.  When 
this  is  done,  the  filling  is  burred  away  with  the  root.  With  this 
method,  there  is  always  a  possibility  of  loosening  the  root  filling, 
and  thus  leaving  a  chance  for  future  trouble. 

The  writer  believes  that  in  an  operation  of  this  kind,  the  most 
satisfactory  and  certain  method  is  to  fill  the  root  after  amputating. 
The  length  of  the  root  is  taken  with  a  hooked  broach,  and  a  canal 
plugger  is  selected  which  will  reach  only  to  within  about  one-eighth 
of  an  inch  of  the  end,  the  same  as  in  the  filling  of  a  root  with  an 
enlarged  foramen. 

The  j>ocket  is  first  treated  the  same  as  for  an  acaite  abscess, 
being  washed  out  with  hydrogen  peroxide,  followed  with  aromatic 
sulijhuric  acid. 

An  instrument  having  a  broad  fiat  end  is  j)assed  through  the 
opening  in  the  process  and  pressed  tightly-  over  the  end  of  the  root, 
being  held  firmly  in  that  position  with  the  left  hand.  The  canal 
is  then  thoi^oughly  dried. 

A  gutta  percha  point,  which  has  previously  been  selected  and 
which  is  slightly  larger  than  the  plugger  which  is  to  be  used,  the 
length  being  about  that  of  the  canal  between  the  end  of  the  plugger 
and  the  end  of  the  root,  is  fastened  to  the  i)lugger  point  by  heating. 
This  is  dipped  in  eucalyptus  oil  and  packed  tightly  against  the 
instrument  which  covers  the  end  of  the  root.  H\  filling  the  root 
in  this  way,  we  may  be  (piite  sure  that  the  filling  is  firm,  and  there 
will  ])('  no  liability  of  leakage. 


32  PATHOLOGICAL  CONDITIONS 

If  the  crown  of  the  tooth  is  good,  and  the  canal  is  not  to  be  used 
for  the  reception  of  a  post,  the  entire  canal  may  be  filled  with  the 
gutta-percha,  packing  it  tightly  against  the  instrument  covering 
the  end  of  the  root. 

If  the  wound  is  large,  it  is  better  that  it  be  packed  lightly  with 
antiseptic  gauze,  which  will  act  as  a  seton  and  keep  the  part  drained. 
This  dressing  should  be  changed  every  two  or  three  days  and  the 
wound  washed  out  with  an  antiseptic  solution.  Healthy  granulation 
will  quickly  begin  and  the  depth  of  the  wound  will  diminish  as  it  is 
filled  in  with  healthy  tissue.  The  treatment  should  be  kept  up 
until  the  wound  has  become  filled  with  healthy  tissue  to  within  about 
one-quarter  of  an  inch  of  the  opening.  The  dressing  and  washing 
may  then  be  discontinued.  Healing  will  be  complete  within  a  very 
short  time,  if  all  of  the  necrosed  tissue  has  been  removed.  If 
this  does  not  take  place,  it  is  evidence  that  there  is  still  remaining 
some  diseased  tissue,  and  further  treatment,  looking  to  its  removal, 
is  needed. 


CHAPTER  III. 

CROWN  AND  BRIDGE-WORK  IN  RELATION  TO  THE 

VITALITY  OF  THE   PULPS  IN  SUPPORTING 

TEETH. 

For  many  years  it  was  a  question  as  to  whether  it  were  l)est  to 
devitalize  a  tooth  preparatory  to  crowning,  or  to  preserve  the  pulp 
alive.  There  was  rarely  held  a  dental  meeting  of  any  importance 
where  this  subject  was  not  discussed.  ]\Iuch  was  said  both  for  and 
against  devitalizing,  some  claiming  that  the  pulp  should  always  be 
retained  wherever  it  was  possible,  devitalizing  used  only  as  a  last 
resort,  while  others  held  an  opposite  opinion. 

The  ^^Titer  himself,  at  the  beginning  of  his  work,  considered  it 
almost  a  capital  offence  to  destroy  a  pulp  if  there  was  any  possible 
way  of  retaining  it  and  still  utilizing  a  tooth  as  an  abutment. 

After  a  time,  however,  it  was  found  that  the  teeth  from  which 
the  pulps  had  been  removed  were  doing  as  good  work,  or  even  giving 
better  results  than  those,  in  which  the  pulps  had  been  preserved. 

The  excessive  irritation  caused  by  removing  the  enamel  (which 
was  necessary  in  order  to  have  a  closely  fitting  band)  and  also  the 
irritation  caused  by  cementing  the  piece  in  place  seemed  to  excite 
an  overstimulation  of  the  pulp,  resulting  in  the  deposition  of 
secondary  dentin,  the  formation  of  pulp-stones,  and  kindred 
troubles. 

It  is  generally  recognized  at  the  present  da\-,  that  the  pulp  is 
purely  a  f(jrmative  organ,  and  after  it  has  performed  its  function 
it  is  no  longer  necessary  to  the  life  and  health  of  the  tooth,  and  a 
tooth  from  which  the  i)uli)  has  been  removed  and  the  canal  has 
been  properly  filled  will  do  the  work  as  a  support  for  a  bridge  as 
well  or  even  better  than  one  in  which  it  has  been  retained. 

Exceptions. — There  are  a  few  exceptions  to  this  rule.  In  the 
case  of  a  patient  of  advanced  years,  where  the  tooth  has  been  broken 
or  worn  down  by  attrition,  so  that  it  can  be  trimmed  or  shaped  witli 
little  or  no  pain,  or  where  the  pulps  of  the  teeth  may  have  receded 
to  such  an  extent  that  the  canals  have  become  nearly  obliterated, 
it  is  permissible,  and  many  times  advisable,  to  crown  such  teeth 
without  undertaking  to  devitalize. 


34  CROWN  AND  BRIDGE-WORK 

In  the  case  of  very  young  subjects  the  teeth  should  never  be 
devitahzed  for  the  purpose  of  placing  a  shell  crown  or  a  bridge,  as 
the  teeth  are  not  then  fully  developed,  and  the  pulps  should  be 
retained  until  the  patient  has  matured  and  the  roots  are  perfectly 
formed.  It  is  rarely  that  pulps  should  be  devitalized  until  the 
patient  is  at  least  seventeen  or  eighteen  years  of  age. 

In  the  case  of  a  very  young  subject,  where  teeth  have  been  lost 
and  the  patient,  perhaps,  has  been  under  orthodontic  treatment, 
and  it  is  necessary  to  bridge  the  space  in  order  to  retain  the  teeth  in 
proper  occlusion,  a  temporary  bridge  may  be  made,  mutilating  the 
teeth  as  little  as  possible,  simply  making  space  enough  between 
those  which  are  to  serve  as  abutments  and  adjoining  teeth  to  allow 
for  the  thickness  of  a  metal  band,  but  not  cutting  through  the  enamel. 
After  the  work  has  been  placed  in  the  mouth,  it  should  be  frequently 
examined  and  a  careful  watch  kept  over  the  patient  until  such  time 
as  it  may  be  advisable  to  insert  a  permanent  fixture. 

THE  CAUSE  OF  SOUND  TEETH  DISCOLORING  AFTER 
DEVITALIZATION. 

There  are  times  when  a  patient  may  object  to  having  one  of  the 
anterior  teeth  devitalized  for  fear  that  it  may  become  discolored. 
If  the  operation  of  devitalizing,  and  the  after-care  of  the  tooth  has 
been  properly  done,  there  will  be  no  discoloration.  The  discolora- 
tion of  a  tooth  from  which  the  pulp  has  been  removed  is  d;ie  not 
to  the  fact  that  the  tooth  has  been  devitalized,  but  to  its  improper 
treatment  after  devitalizing. 

Quoting  from  his  own  experience,  the  writer  does  not  recall  a 
single  case  in  which  a  tooth  has  become  discolored  after  removing 
the  pulp,  but  he  has  seen  and  treated  many  such  cases,  and  has 
invariably  found  unmistakable  evidence  of  the  manner  in  which 
this  condition  was  brought  about. 

The  tooth  is  opened  from  the  lingual  or  palatal  side,  or  through 
a  cavity,  perhaps,  on  the  mesial  or  distal  side,  drilling  in  the  direc- 
tion of  the  apex.  The  pulp  is  removed  through  this  opening  and 
the  canal  cleansed  and  filled.  Usually  it  will  be  found  that  this  part 
of  the  work  has  been  well  done,  but  the  operator  has  not  gone  far 
enough  in  his  work  to  prevent  the  trouble.  As  will  be  seen  in  the 
illustration  (Fig.  9),  the  horn  of  the  pulp  extends  far  up  into  the 
crown  of  the  tooth,  while  the  opening  has  been  made  far  below  it. 
The  result  is  that  this  extension  of  the  pulp  remains  in  the  tooth 


DEVITALIZATION  OF   THE  PULP  35 

after  the  canal  and  cavity  has  been  filled,  as  in  Fig.  9,  where  it 
decomposes,  and  in  time  the  tooth  structure  becomes  infiltrated 
with  this  putrescent  matter  causing  the  discoloration. 

The  writer  does  not  remember,  and  has  no  record  of  ever  ha^•ing 
opened  up  a  discolored  tooth  where  he  has  not  found  the  conditions 
as  described  above. 

After  the  canal  has  been  opened,  the  pujp  chamber  should  be 
enlarged  sufficiently  near  to  the  incisal  edge  of  the 
tooth  to  permit  of  the  removal  of  every  particle 
of  pulp  tissue.  This  can  be  done  with  a  rose 
bur  in  the  right  angle  hand-piece,  working  from 
the  lingual  side,  and  opening  it  up  enough  so  that 
the  extreme  apex  of  the  pulp  chamber  can  be 
reached,  Fig.  10.  After  the  pulp  has  been  entirely 
removed,  the  cavit^'  is  thoroughlv  sterilized  and      ^^     „       t-     ,« 

.     ,     "       ,  Fig.  9     |     Fig.  10 

filled  with  cement  of  any  suitable  color. 

Although,  if  the  work  of  devitalizing  and  filling  a  tooth  be  properly 
done,  there  will  be  no  discoloration  of  the  crown,  there  will  always 
be  a  slight  difference  in  the  opacity,  owing  to  the  removal  of  dentin 
and  the  placing  of  the  cement  lining  which  may  render  it  slightly 
noticeable  in  certain  lights,  or  when  viewed  from  certain  angles. 
This  will  be  especially  true  if  the  tooth  so  treated  is  standing  next 
to  its  mate,  as  would  be  the  case  if  one  of  the  centrals  was  devi- 
talized. With  the  cuspid,  there  are  so  many  teeth  between  it  and 
the  corresponding  tooth  on  the  opposite  side  of  the  mouth,  that 
even  a  marked  difference  in  color  would  not  be  in  the  least  conspic- 
uous. The  following  may  be  set  down  as  a  rule  which  should 
invariably  l)e  observed. 

Where  there  is  a  choice  of  teeth,  one  of  which  is  to  be  devitalized 
to  serve  as  an  abutment  for  a  bridge,  always  devitalize  the  tooth 
which  danda  farthest  away  from  its  vuite. 

In  the  case  of  a  lost  lateral,  the  cuspid  and  central  being  in  equally 
good  condition,  the  cuspid  should  be  used  as  the  abutment,  but 
if  the  central  incisor  is  badly  decayed  or  broken,  then  of  course 
it  will  be  policy  to  utilize  it. 

DEVITALIZATION    OF    THE   PULP. 

When  it  is  found  necessary  to  deviudize  the  pulp  of  a  tooth  |)rior 
to  its  preparation  for  an  artificial  crown,  there  are  several  (juestions 
to  be  considered.     The  first  of  these  is:    In  which  of  the  methods 


36  CROWN  AND  BRIDGE-WORK 

that  may  be  employed  is  there  the  least  danger  of  irritation  or 
injury  to  the  tooth  or  its  adjacent  parts?  (2)  In  what  way  may  the 
operation  be  performed  with  the  least  pain  to  the  patient?  (3) 
How  can  it  be  most  quickly  and  easily  accomplished'' 

Arsenic. — There  are  several  methods  and  agents  employed  for 
the  devitalization  of  the  pulp,  any  of  which  may  be  indicated  under 
certain  conditions.  Among  the  agents  that  are  generally  used  for 
this  purpose,  arsenious  acid  has  been  longest  in  use  and  more 
generally  employed.  It  is  the  one,  however,  which  requires  the 
greatest  care  in  its  use;  is  dangerous  in  unskilled  hands,  and  is  not 
always  certain  in  its  action. 

Dr.  Herman  Prinz's  Method. — Innumerable  formulas  for  compounds 
of  arsenic  with  other  drugs  are  suggested  for  dental  purposes.  The 
principal  object  has  always  been  to  combine  the  arsenic  with  an  anes- 
thetic. If  the  pulp  is  in  a  normal  condition,  very  little  or  no  pain 
is  manifested  by  the  arsenical  application;  if  the  nerve  cells  are 
inflamed  or  are  undergoing  necrobiotic  changes,  the  increased  irri- 
tation brought  about  by  the  powerful  oxidation  and  reduction  as  a 
result  of  the  pharmacologic  action  of  arsenic  increases  the  already 
existing  neuritis  and  more  or  less  severe  pain  results.  Arsenic 
is  very  diffusible;  it  quickly  destroys  the  nerve  endings,  and  con- 
sequently there  is  little  chance  for  the  anesthetic  which  may  be 
added  to  it  to  exercise  its  specific  function.  For  this  very  reason  it 
is  questionable  if  the  addition  of  a  local  anesthetic  is  of  any  benefit. 

A  more  rational  procedure  consists  in  applying  to  an  aching  pulp 
a  concentrated  solution  of  a  local  anesthetic-cocaine,  novocain, 
etc.,  prior  to  the  introduction  of  the  arsenical  paste.  Tanning 
agents  are  frequently  added  to  the  paste  for  the  purpose  of  changing 
the  pulp  tissue  to  a  leathery, material,  so  as  to  facilitate  its  ready 
removal. 

Tannic  acid  or  the  various  forms  of  formaldehyde  are  useful 
for  this  purpose.  It  is  better  practice  to  apply  such  agents  after 
the  arsenic  dressing  has  been  removed;  the  less  we  interfere  with 
the  absorption  of  the  arsenic,  the  better  and  quicker  will  be  the 
results. 

As  a  vehicle  for  the  paste,  only  such  media  as  are  more  or  less 
solvents  of  arsenic,  and  which  allow  ready  absorption  by  the  pulp, 
are  justified.  Glycerin  is  preferable  to  any  other  medium.  Lanolin, 
a  natural  wool  fat,  has  been  recommended;  it,  however,  prevents 
the  ready  absorption  of  the  paste.  Phenol,  creosote,  or  the  essen- 
tial oils,  and  similar  liquids,  have  been  used  for  many  years  as 


DEVITALIZATION  OF   THE  PULP  37' 

vehicles  for  the  paste;  their  influence  on  the  action  of  arsenic  is 
apparently  of  very  little  consequence;  they  certainly  do  not  exercise 
their  typical  pharmacologic  action  in  this  connection.  Strong 
coagulants  should  not  be  used,  as  they  hinder  the  ready  absorption 
of  the  poison  by  forming  a  scab. 

To  give  a  distinct  color  to  the  paste,  very  small  quantities  of 
carmine  or  lampblack  may  be  added.  Some  practitioners  prefer 
to  apply  arsenic  in  the  form  of  a  paste  mixed  with  cotton  fibers, 
or  in  the  form  of  paper  disks  saturated  with  a  soft  paste.  Arsenical 
fiber  is  prepared  by  mixing  cross-cut  cotton  with  the  paste,  and  the 
disks  are  made  by  saturating  very  small  squares  of  hard  white 
blotting  paper  with  the  thin  paste,  which  are  then  dried  and 
preserved. 

Prior  to  the  application  of  arsenic,  the  cavity  should  be  excavated, 
and  if  possible  the  pulp  should  be  thoroughly  depleted,  either  by 
puncturing  the  organ  or  by  producmg  artificial  anemia.  Szabo 
recommends  lavage  for  this  purpose — washing  the  pulp  with  hike 
warm  water,  changed  slowly  to  cold  water.  Quicker  results  are, 
however,  obtained  by  applying  adrenalin  chloride  solution  under 
pressure. 

The  cavity  must  be  free  from  blood,  to  prevent  the  formation  of 
inactive  arsenic  hemoglobin.  If  the  pulp  is  inflamed  and  painful, 
it  is  absolutely  necessary  to  apply  suitable  remedies  to  relieve  the 
conditions  before  the  paste  is  applied;  an  inflamed  j)ulp  materially 
hinders  the  ready  absorption  of  arsenic,  and  continuous  servere 
pain  is  certain  to  follow.  A  mixture  of  tannic  acid,  cocain  hydro- 
chlorid,  and  liquid  phenol  is  serviceable  for  this  purpose.  These 
remedies,  if  sealed  into  the  cavity,  usually  alleviate  the  condition 
in  from  twenty-four  to  forty-eight  hours. 

If  pus  is  present,  it  must  be  drained  oft',  and  washed  away  with 
a  mild,  warm  antiseptic  solution.  Pulp  nodules  occasionally  obstruct 
the  ready  diftusibility  of  the  chemical.  Removal  of  these  calcareous 
deposits  by  means  of  sulphuric  acid  or  by  a  drill,  after  cocain 
pressure  anesthesia  has  been  applied,  is  indicated.  Cocain  should 
never  be  applied  cataphorically  under  these  conditions,  as  the  electric 
current  will  drive  the  previously  applied  arsenic  through  the  a])ical 
fijramen  into  the  soft  tissues.  Occasionally  one  meets  a  ])atient 
who  presents  an  unexplained  idiosyncrasy  to  the  action  of  this 
chemical. 

TIk;  cavity  lor  tiie  recejAion  of  the  arsenical  aj)i)lication  should 
l)e  of  ready  access,  and  so  jjrepared  as  to  easily  retain  the  temporary 


38  CROWN  AND  BRIDGE-WORK 

filling.  The  arsenical  compound  is  preferably  placed  in  direct 
contact  with  the  freely  exposed  pulp  by  means  of  a  blunt  instrument, 
or  on  a  depressed  metallic  disk  or  a  piece  of  cardboard,  or  on  cotton 
or  spunk.  Close  contact  insures  quick  action.  Arsenic  will  act 
by  osmosis,  although  slower,  through  any  thickness  of  dentin. 
This  very  fact  is  the  reason  its  use  as  a  remedy  for  hypersensitive 
dentin  has  been  abandoned;  death  of  the  pulp  was  invariably  the 
sequence  of  such  a  procedure.  Some  operators  prefer  to  cover  the 
arsenical  dressing  with  an  intermediate  film  of  plain  or  oiled  paper, 
or  pledget  of  cotton.  The  final  sealing  of  the  cavity  consists  of  a 
temporary  filling  of  cement  or  of  a  gutta-percha  preparation. 

Extreme  care  should  be  exercised  in  this  simple,  yet  most 
important  operation.  Cotton  fibers  mixed  with  sandarac  or  mastic 
varnish,  to  be  used  as  a  retaining  medium  should  be  avoided ;  they 
readily  become  foul  in  the  fluids  of  the  mouth,  or  they  may  leak,  and, 
besides,  they  swell,  causing  pain  from  pressure  on  the  pulp.  Kirk 
has  advocated  the  use  of  surgeon's  rubber  plaster  where  but  a 
portion  of  the  tooth  is  left,  carrying  it  around  the  tooth;  it  will 
adhere  satisfactorily  for  several  days,  or  long  enough  to  accomplish 
the  object.  The  gutta-percha  preparations  are  the  best  media  for 
a  temporary  dressing  seal;  most  experienced  operators  agree  that 
a  cavity  correctly  sealed  with  this  material  ofters  less  possibilities 
for  the  seeping  through  than  the  various  cements  or  other  materials. 
In  Europe  Fletcher's  artificial  dentin  is  used  universally  for  such 
work.  In  applying  the  temporary  stopping,  it  is  very  essential 
to  avoid  pressure  on  the  dressing.  In  approximal  cavities,  where 
overhanging  tooth  substance  prevents  ready  access,  and  therefore 
presents  danger  of  misplacing  the  arsenical  dressing,  gutta-percha 
packed  between  the  two  teeth,  and  thus  acting  as  a  splint,  is  of 
service."    (Prinz.) 

The  writer  believes  that  it  is  best  to  avoid  the  use  of  arsenic  if 
this  can  be  done,  as  there  is  always  a  possibility  of  disturbances 
following  its  use,  such  as  arsenical  pericementitis  or  even  necrosis. 
The  former  of  these  may  not  manifest  itself  immediately,  but 
sooner  or  later  it  may  appear  either  in  a  mild  or  an  aggravated  form. 

If  the  arsenic  is  not  sealed  in  perfectly,  especially  if  the  cavity 
extends  below  the  gingival  margin,  necrosis  is  sure  to  ensue,  which 
in  some  cases  might  have  far-reaching  effects.  Some  patients 
are  peculiarly  susceptible  to  this  poison;  and  in  the  mouths  of  such, 
arsenic  applied  for  a  few  hours  only  would  be  sufficient  to  devitalize 
the  pulp  completely,  while  in  others  it  might  remain  for  days  with 


DEVITALIZATION  OF  THE  PULP  39 

seemingly  little  effect.  In  the  former  case,  if  it  were  left  in  the  tooth 
for  an\-  great  length  of  time,  it  is  almost  certain  that  its  action  wonld 
not  be  limited  to  the  pulp  itself,  but  would  extend  through  the 
foramen  and  beyond  the  apex  and  involve  the  surrounding  tissue. 
Especially  would  this  be  true  if  the  foramen  were  somewhat  enlarged. 
The  danger  would  be  greater  when  usmg  it  on  a  young  patient 
than  on  an  elderly  patient,  as  in  the  former  the  root  may  not  be 
fully  developed,  and  the  foramen  be  widely  patulous,  in  which  cases, 
carbolic  acid,  creosote  or  some  such  agent  is  indicated. 

Cases  also  occur  in  which  there  is  an  imperfection  in  the  walls 
of  the  root-canals.  A  condition  of  this  kind  is  fortunately  very 
rare  and  it  is  one  which  it  is  impossible  to  foresee  and  guard  against. 
If  arsenic  is  used,  disturbances  which  may  result  in  serious  injury 
to  the  patient  are  unavoidable.  Very  rarely  it  may  hap])en  that 
the  pulp  will  resist  the  arsenic  and  repeated  applications  will  have 
no  effect,  in  which  event,  some  other  method  of  devitalization 
must  be  employed,  although  it  will  generally  be  fonnd  that  where 
the  pulp  resists  the  action  of  the  arsenic  it  is  also  likely  to  resist 
the  action  of  any  other  drugs  which  may  be  used. 

By  far  the  safest  and  most  rapid  method  is  immediate  devitaliza- 
tion. There  are  several  different  ways  of  accomplishing  this  by 
surgical  means,  either  by  the  use  of  a  general  or  a  local  anesthetic 
and  extirpating  the  pulp  at  once  with  broaches  or  by  using  what 
was  termed  the  heroic  method.  This  latter  consists  of  driving  the 
pulp  out  with  a  pointed  orange-wood  stick  without  anesthetizing. 
Since  the  aflvent  of  pressure  anesthesia,  this  method  has  become 
nearly  obsolete,  but  there  are  still  occasions  where  it  can  be  used 
to  advantage  and  a  few  words  descriptive  of  the  technique  will 
not  be  out  of  i)lace. 

The  Heroic  Method. — This  method  was  successfully  emplo.N'ed, 
wherever  jjossible,  for  many  years  by  numbers  of  dentists  who 
feared  the  use  of  arsenic.  It  was  characterized,  by  some  as  being 
barbarons,  and  in  fact,  to  one  not  familiar  with  the  operation  it 
might  seem  to  be  so,  but  there  are  times  where  it  is  indicated  and 
if  the  operation  is  skilfully  performed,  it  is  instantaneous  in  accom- 
plishing the  result  and  comes  as  near  being  painless  as  any  method 
that  can  be  employed. 

It  is  especially  indicated  in  the  anterior  part  of  the  mouth  and 
for  single-rooted  teeth  wlicre  there  is  a  full  exposure  of  the  pulp, 
as  in  the  case  of  a  Utoth  bnjken  off  from  a  blow,  leaving  the  jnilp 
protruding. 


40 


CROWN  AND  BRIDGE-WORK 


In  employing  this  method  of  pulp  extirpation,  the  pulp  must  be 
well  exposed  and  the  operator  should  have  a  clear  idea  as  to  the 
general  shape  and  size  of  the  pulp  canal  of  the  tooth  to  be  operate 
upon.  The  end  of  an  orange-wood  stick  is  whittled  to  correspond 
in  size  to  the  canal,  and  is  placed  within  convenient  reach  together 

with  a  heavy,  loaded  mallet 
(Figs.  11  and  12). 

If  the  crown  of  the  tooth 
is  to  be  removed,  it  may  be 
cut  as  nearly  through  as 
possible  by  making  a  groove 
labially  and  lingually  with 
a  thin  carborundum  disk 
and  then  it  is  nipped  off 
with  excising  forceps  (Fig. 
13). 

The  rubber  dam  should 
be  applied  wherever  it  is 
possible  to  do  so.  This  hav- 
ing been  done,  the  point 
of  the  orange-wood  stick  is 
dipped  in  carbolic  acid  and 
placed  at  the  entrance  of 
the  canal  and  a  quick,  sharp 


Fig. 11 


Fig.  12 


Fig.  13 


blow  given  it  with  the  mallet.  If  the  orange-wood  has  been 
properly  shaped,  the  pulp  will  be  forced  out  between  the  canal 
wall  and  the  stick,  or  will  be  found  clinging  to  the  latter  when  it 
is  withdrawn.  If  this  does  not  occur  and  any  of  the  pulp  remains 
in  the  canal,  it  is  carefully  removed  with  barbed  broaches.  The 
canal  is  then  thoroughly  cleansed,  sterilized  and  filled. 

This  method  is  especially  applicable  to  the  single-rooted  teeth, 
but  it  has  been  successfully  employed  in  the  upper  first  bicuspids 


TREATMENT  OF  INFLAMED  AND  ACHING  PULPS        41 

and  under  favorable  conditions,  even  to  the  larger  canals  in  molars 
where  the  crowns  have  been  so  badly  broken  down  as  to  render  the 
canals  easily  accessible.  In  the  upper  molars,  if  the  body  of  the 
pulp  has  been  removed,  that  portion  in  the  palatal  canal  may  almost 
always  be  removed  in  this  way,  but  the  buccal  canals  are  generally 
too  small  and  difficult  of  access.  In  the  lower  molars  the  pulp  in 
the  canal  of  the  distal  root  can  be  extracted,  but  in  the  mesial 
canals  there  would  be  the  same  trouble  as  in  the  buccal  canals 
of  the  upper  molars. 

The  operation  is  performed  so  quickly  that  the  pulp  is  paralyzed 
by  the  shock,  and  the  pain  should  be  no  greater  than  that  felt  from 
the  slight  prick  of  a  pin.  This  happy  result  depends  entirely  upon 
the  careful  following  out  of  the  technique,  for  at  the  hands  of  an 
awkward  manipulator  it  might  cause  the  patient  a  great  deal  of 
pain 

TREATMENT  OF  INFLAMED   AND   ACHING   PULPS   PREPARA- 
TORY  TO  DEVITALIZING. 

It  should  always  be  borne  in  mind  that  neither  arsenic  nor  an 
anesthetic  will  act  upon  an  inflamed  or  congested  pulp.  If  the  pulp 
is  in  this  condition,  it  has  been  the  experience  of  the  writer  that  a 
dressing  of  oil  of  cloves  or  eugenol  and  sulphate  of  morphia  is  one 
f)f  the  best  applications  for  relieving  the  pain  and  reducing  the 
inflammation.  A  pellet  of  cotton  is  saturated  with  the  oil  of  cloves 
or  eugenol  and  from  one  fortieth  to  one  thirtieth  of  a  grain  of  the 
morjjhia  is  added  to  it.  This  is  ])la('ed  in  the  cavity  and  allowed 
to  remain  until  the  pulp  is  quiescent,  which  will  usually  be  in  from 
twenty-four  to  forty-eight  hours,  after  which  the  arsenic  or  the 
anesthetic  may  be  ai)pli('d. 

Pressure  Anesthesia  as  Used  in  the  Removal  of  the  Pulp. — 
With  the  introduction  of  pressure  anesthesia  the  work  of  devitalizing 
and  removing  pulps  has  been  very  much  simplified. 

A  number  of  instruments  have  been  d('\  iscd  for  anesthetizing 
the  pulp  through  the  crown  of  the  tooth.  These  are  in  the  form  of 
a  fjowerful  syringe,  by  means  of  wliicli  great  |)r('ssnre  can  be 
obtained. 

An  o|)cning  is  made  tlirongli  the  enainci  to  tlic  dentin  with  a 
small  bur,  corresj)onding  in  size  to  the  point  of  tlie  syringe,  which 
is  tli<'n  i)lafed  in  this  opening,  and  pressure  applied  to  force  the 
anesthetic   into   the   tooth    structure.      if    the   point    (its    (he   hole 


42  CROWN  AND  BRIDGE-WORK  . 

accurately,  in  a  majority  of  cases  a  satisfactory  anesthesia  will 
be  obtained.  Many  times,  however,  the  syringe  point  does  not 
accurately  fit  the  hole  through  the  enamel,  the  anesthetic  escapes 
around  it  instead  of  being  forced  into  the  dentin,  and  in  conse- 
quence the  application  is  ineffective. 

Another,  and  in  fact  the  original  method,  is  to  place  the  anes- 
thetizing solution  into  a  carious  cavity,  or  an  opening  made  for 
the  purpose,  and  over  this  a  piece  of  un vulcanized  rubber  is  placed. 
This  is  pressed  into  the  cavity  with  a  strong  instrument,  forcing 
a  sufficient  quantity  of  the  solution  into  the  tooth  structure  to 
produce  a  satisfactory  anesthesia.  This  latter  method  is  the  one 
preferred  by  the  writer.  It  the  proper  technic  is  carefully  followed 
positive  and  satisfactory  results  may  be  confidently  expected. 

One,  and  perhaps  the  principle  cause  of  failure  in  applying  the 
pressure  in  this  manner,  is  that  the  operator  uses  for  carrying  the 
solution  a  piece  of  cotton  entirely  too  large  for  the  purpose.  The 
cotton  is  dipped  into  the  anesthetic  solution,  placed  in  the  cavity 
and  the  pressure  applied.  If  the  mass  of  cotton  is  too  large  to  be 
covered  by  the  rubber,  some  fibers  are  left  projecting  from  the  sides 
of  the  cavity;  when  the  pressure  is  applied,  these  give  vent  to  the 
solution,  so  that  instead  of  its  being  forced  into  the  tooth  structure, 
it  escapes  by  following  the  cotton  fibers  extending  over  the  edge 
of  the  cavity. 

It  must  be  remembered  that  in  applying  pressure  anesthesia  in 
any  manner  whatsoever,  that  the  pressure  must  be  direct  and 
positive,  without  any  leakage,  in  order  to  force  the  solution  into 
the  dentin  or  into  the  pulp. 

Sterile  Field  for  Operation. — Before  applying  pressure  anesthesia 
the  greatest  care  must  be  used  to  insure  a  sterile  field  for  the  opera- 
tion. If  there  is  a  gangrenous  or  septic  condition  of  the  body  or 
any  part  of  the  pulp,  this  must  first  be  corrected  and  the  parts  made 
as  thoroughly  aseptic  as  possible.  If  this  is  not  done,  septic  gases 
or  matter  may  be  forced  through  the  apical  foramen  and  cause 
serious  trouble. 

In  order  to  devitalize  a  perfectly  sound  tooth,  an  opening  should 
be  made  directly  on  line  with  the  axis  of  the  tooth  so  as  to  gain 
direct  and  free  access  to  the  pulp.  The  first  step  is  to  grind  through 
the  enamel.  This  is  best  done  with  a  small  stump  carborundum 
point,  or  a  diamond  disk  or  drill.  The  engine  should  be  run  rapidly 
and  the  tooth  kept  flooded  with  iced  water,  which  prevents  heat- 
ing, and  also  acts  as  a  slight  obtundent.    By  using  ice-water  freely. 


TREATMENT  OF  INFLAMED  AND  ACHING  PULPS        43 

the  enamel  can  be  quickly  pierced,  sometimes,  even  continued  until 
the  pulp  is  exposed,  with  but  little  or  no  pain  at  all  to  the  patient. 
In  the  anterior  teeth  this  opening  is  made  on  the  palatal  or  lingual 
side,  while  in  the  bicuspids  and  molars  it  is  made  directly  through 
the  center  of  the  tooth.    Fig.  14. 

The  rubber  dam  is  applied  as  soon  as  the  enamel  has  been  pene- 
trated. If  from  any  cause  this  cannot  be  done,  napkins  may  be 
substituted  to  keep  the  secretions  of  the  mouth  from  encroaching 
upon  the  field  of  operation. 

The  instruments  needed  should  be  ready  at  hand,  convenient 
for  instant  use.    These  shoukl  include  broaches  for  removing  the 


9  e 


Fig.  14 


Fig.  15 


Fig.  16 


Fig.  17 


pulp  from  the  canals,  a  large  spear-pointed  drill,  large  coarse  rose 
burs,  a  large  cross-cut  fissure  bur,  and  one  or  two  sharp  spoon 
excavators  which  may  be  used  to  remove  the  body  of  the  pulp. 

A  large  spear-pointed  drill  is  the  best  instrument  for  drilling 
through  the  dentin  (Fig.  15).  It  should  not  be  used  for  drilling 
through  the  enamel,  as  the  latter  is  so  hard  that  it  c^uickly  dulls  the 
point,  with  the  result  that  it  not  only  takes  more  time,  but  the 
increased  pressure  necessary  to  make  it  cut,  heats  the  tooth,  and 
renders  the  ojjeration  much  more  painful  than  it  would  be  otherwise. 

It  is  very  rarely  these  instruments  are  well  made  as  they  come 
from  the  dental  depots.  They  are  generally  too  thick  and  at  the 
cutting  edges  are  not  backed  off  sufficiently  to  cut  well.  They  can 
be  greatly  improved  by  first  grinding  them  very  thin  and  then 
backing  them  off  so  as  to  leave  a  good  sharp-cutting  edge  which 
will  cut  deeply  and  cleanly  into  the  denti?ie  and  clear  itself  readily. 
(Fig.  10).  If  the  edges  are  thick  and  straight  across  and  have  not 
this  clearance  (Fig.  17),  the  drill  will  drag  and  heat,  causing  i)ain  and 
rendering  the  f)peration  more  lengthy  and  diflienlt. 

The  enamel  having  been  picTced,  the  rubber  dam  is  applied,  the 
tooth  thoroughly  dried,  and  the  point  of  the  drill  placed  on  the 


44  CROWN  AND  BRIDGE-WORK 

dentin  pointing  in  direct  line  with  the  axis  of  the  tooth's  root, 
with  the  engine  running  at  high  speed.  As  soon  as  the  patient 
experiences  pain,  it  is  time  to  begin  the  use  of  pressure  anesthesia. 

Ethyl  chloride  may  also  be  used  in  making  the  exposure.  In 
drilling  the  opening,  when  the  tooth  begins  to  be  sensitive,  the 
spray  should  be  applied,  intermittently  at  first,  touching  the  tooth 
only  for  an  instant,  repeating  at  short  intervals,  each  time  keeping 
it  on  for  a  little  longer  period,  until  the  tooth  becomes  insensible. 
In  this  way  the  tooth  is  cooled  gradually  and  the  pain  or  shock 
which  occurs  when  the  spray  is  applied  directly  and  continuously 
is  avoided.  The  spear-pointed  drill  is  now  used,  and  if  the  tooth 
again  becomes  sensitive  before  the  pulp  is  reached,  the  spraying  is 
repeated. 

There  are  a  number  of  different  preparations  used  in  the  devi- 
talization or  the  anesthetizing  of  the  pulp.  Novocain  seems  to 
be  a  favorite  agent  with  many  dentists.  The  writer,  however,  has 
had  excellent  results  from  using  the  pure  crystals  of  cocain  in  con- 
junction with  some  fluid  as  a  vehicle,  usually  favoring  a  local 
anesthetic  solution. 

The  local  anesthetic,  which  seems  to  work  best,  and  in  fact,  has 
been  found  by  the  writer  superior  either  for  extracting  or  wherever 
a  local  anesthetic  is  indicated,  is  as  follows: 

Acid,  carbolic 10  gr. 

Cocain  hydrochlorid 10  gr. 

Atropia  sulphate 2  per  cent,  solution  10  min. 

Nitroglycerin 1  per  cent,  solution  10  min. 

Adrenalin  chlorid Sol.  (1  :  1000)  10  min. 

Distilled  water 2  oz. 

After  using  and  recommending  it  for  nearly  twenty  years,  the 
writer  has  neither  seen  nor  heard  of  any  ill  results  following  its  use. 
It  is,  however,  wise  to  use  this,  and  all  allied  preparations  with 
caution,  using  no  more  than  is  absolutely  needed. 

In  making  the  application,  only  a  very  minute  piece  of  cotton 
should  be  used.  A  piece  no  larger  than  one-quarter  the  size  of  a 
pin  head  is  ample  for  the  largest  tooth.  This  is  dipped  in  the  anes- 
thetic solution  and  then  a  slight  excess  of  the  cocain,  which  has 
previously  been  finely  powdered  on  a  glass  slab,  is  taken  up  on 
the  cotton  and  it  is  placed  at  the  bottom  of  the  cavity. 

A  piece  of  soft,  unvulcanized  rubber  is  then  placed  over  it  and 
pressure  brought  to  bear  with  an  instrument  which  nearly  fills  the 
opening.     It  must  be  remembered  that  in  order  to  obtain  perfect 


TREATMENT  OF  INFLAMED  AND  ACHING  PULPS        45 

results  there  must  be  a  positive  pressure,  and  if  the  instrument  be 
too  large  or  too  small  it  will  not  do  the  work  as  well.  If  a  positive 
pressure  is  obtained,  it  is  not  necessary  to  keej)  it  up  longer  than 
from  twenty  to  thirty  seconds.  The  vulcanite  and  the  pellet  of 
cotton  are  then  removed,  the  opening  dried,  and  the  spear-pointed 
drill  is  once  more  used. 

If  the  tooth  becomes  sensitive  again  before  the  pulp  is  exposed, 
the  operation  is  repeated.  It  will  be  found,  however,  that,  as  a 
general  rule,  with  one  or  two  aj)plications  of  the  anesthetic,  the 
exposure  can  be  obtained,  without  i)ain  to  the  patient.  After  the 
exposure  has  been  made,  the  final  ajiplication  should  be  made 
directly  on  the  pulp,  the  pressure  being  kept  up  for  about  thirty 
seconds,  when  it  will  be  found  that  the  \n\\\y  has  been  completely 
anesthetized  and  the  i)uli)  chamber  can  be  opened  and  the  pulp 
removed. 

It  should  be  remembered  that  in  using  the  anesthetic  with 
pressure,  the  pulj)  is  not  devitalized,  but  simply  anesthetized,  and 
if  the  operation  of  removing  the  pulp  is  long  continued,  sensation 
may  return.  In  multi-rooted  teeth,  when  the  canals  are  very 
minute  and  difficulty  is  ex]>erienced  in  opening  into  them,  sensation 
may  return  to  the  pulp  of  one  or  two  of  the  canals  while  the  pulp 
was  being  removed  from  the  others.  This  necessitates  a  second 
application. 

If  the  tooth  has  been  broken  down  by  decay  and  a  cavity  exists 
through  which  the  pulp  is  accessible,  this  cavity  may  be  utilized. 
The  disintegrated  tissue,  however,  must  first  be  thoroughly  removed, 
for  its  presence  will  hinder  the  action  of  the  drug.  The  anestheti- 
zing solution  on  a  small  pellet  of  cotton  is  then  placed  in  the  cavity, 
and  pressure  applied  as  before  described. 

If  the  pulp  cavity  is  freely  exposed,  the  anesthetic  may  be 
injected  into  it  with  a  hypodermic  syringe.  This,  however,  is 
more  painful,  and  possesses  no  advantage  over  the  method  just 
described. 


CHAPTER  IV. 
THE  PULP  CANALS. 


POSITION    OF    THE   PULP    CANALS. 

Before  undertaking  to  remove  the  pulp  from  devitalized  teeth, 
the  operator  should  have  an  accurate  knowledge  of  the  anatomy 
of  the  teeth.  He  should  know  the  number  of  roots  which  each 
tooth  should  possess,  and  where  to  look  for  entrance  to  the  canals 
on  the  floor  of  the  pulp  chamber  of  a  normal  tooth,  and  should  also 
be  able  to  form  some  idea  of  their  approximate  size. 

Some  of  the  canals  are  frequently  very  minute  and  difficult  to 
locate,  and  a  knowledge  of  their  normal  position  is  helpful  in 
finding  them. 

All  operations  are  more  quickly  and  thoroughly  done  if  the 
operator  works  systematically,  and  by  some  well-considered  rule. 
This  applies  with  much  force  to  the  operation  of  locating  and 
opening  the  pulp  canals. 

Opening  into  the  Pulp  Chamber  of  Molar  Teeth. — Li  enlarging  the 
entrance  to  the  pulp  chamber  do  not  fear  to  make  a  large  opening. 

It  is  impossible  to  get  into  the  different 
canals  in  the  molars,  and  cleanse  them  as 
they  should  be  cleansed,  through  a  minute 
opening  in  the  crown  of  the  tooth.  A 
large  opening  should  be  made  through  the 
crown,  and  the  pulp  chamber  opened  to  its 
full  size  so  that  the  entrance  to  every  canal 
is  easily  accessible.  It  does  not  weaken 
the  tooth  to  do  this.  As  a  chain  is  only 
as  strong  as  at  its  weakest  point,  so  with 
a  tooth,  and  this  point  is  where  the  pulp 
chamber  approaches  the  sides  of  the  tooth  (Fig.  18). 

After  drilling  into  the  pulp  chamber,  the  enamel  at  the  entrance 
to  the  cavity  should  be  removed  with  a  cross-cut  fissure  bur,  but 
the  use  of  this  bur  should  not  extend  to  the  pulp  chamber.  The 
best  instrument  to  enlarge  this,  is  a  large  rose  bur,  passing  it  through 


Fig.  18 


Fig.  19 


POSITION  OF   THE  PULP  CANALS 


47 


the  opening  and  under  the  ledge,  or  as  it  might  be  termed,  the  roof 
of  the  pulp  chamber,  and  pulling  the  bur  toward  the  occlusal 
surface  (Fig.  19). 

This  should  be  continued  until  the  explorer  shows  that  the  sides 
of  the  cavity  are  flush  with  the  sides  of  the  pulp  chamber  and  the 
explorer  slides  smoothly  into  it. 

A  fissure  bur,  an  inverted  cone,  or  any  square-ended  instrument 
should  not  be  used  in  doing  this  work,  as  they  are  sure  to  strike 
the  sides  of  the  pulp  chamber,  leaving  ledges  or  grooves  on  which 
the  broaches  will  catch,  and  render  the  locating  of  the  canals  much 
more  difficult;  whereas,  by  using  round  burs  only,  the  floor  of  the 
pulp  chamber,  is  not  marred,  there  will  be  no  roughness  to  inter- 
fere with  the  instrument,  which  will  then  much  more  readily  find 
the  openings  to  the  different  canals. 


1 


Fig.  20. — a,  Kerr  Ijroaches;   b,  K<jir  ctuinl  files. 


Locating  the  Pulp  Canals  of  the  Upper  Molars. — As  a  rule,  it  is 
more  convenient  to  first  locate  the  i)alatal  canal  in  the  upper  molars. 
This  canal  is  much  larger,  and  occupies  a  position  which  renders 
it  more  easy  of  access  than  are  the  others,  anfl  it  is  rarely  that  there 
is  any  trouble  in  locating  it  at  once  and  removing  the  pulp. 

The  writer  has  found  that  the  best  instruments  for  locating  the 
canals  are  the  short,  knob-handled  broaches  of  the  Kerr  or  Downey 
type  (Fig.  20).  These  instruments  are  made  of  triangular  steel 
wire,  twisted,  and  brought  to  a  fine  j)oint.  They  are  much  stronger 
and  are  less  liable  to  be  broken  than  are  the  barbed  broaches. 
Then,  too,  being  shorter,  without  l)arbs,  and  with  just  the  right 
degree  of  stiffness,  they  afhnit  of  a  far  more  delicate  sense  of  tone!) 
than  docs  a  long  and  very  flexible  instruniciit. 


48  THE  PULP  CANALS 

When  using  these  broaches,  if  conditions  peimit,  the  rubber  dam 
should  always  be  in  place,  but  if  this  is  not  possible,  the  mouth  should 
be  protected  with  napkins,  so  as  to  keep  the  parts  dry,  and  also, 
if  the  broach  should  slip  from  the  fingers,  to  prevent  its  dropping 
into  the  throat. 

The  palatal  canal  having  been  located,  the  next  one  to  look  for  is 
the  anterior  buccal.  To  reach  this,  the  handle  of  the  broach  is  passed 
distally  and  palatally,  reaching  the  point  of  the  instrument  far 
forward  toward  the  mesiobuccal  corner  of  the  tooth,  and  if  the 
pulp  chamber  has  been  carefully  opened,  there  will  be  very  little 
difficulty  in  finding  this  canal.  It  sometimes  happens  that  the 
entrance  to  this  canal  is  located  so  far  mesially  that  it  will  be  neces- 
sary to  cut  entirely  through  the  mesiobuccal  corner  of  the  tooth 
in  order  to  get  free  access  to  it. 

There  still  remains  the  distal  canal  to  be  accounted  for.  If, 
when  the  instrument  is  in  the  anterior  buccal  canal,  it  is  slowly 
withdrawn,  sliding  the  point  lingually  through  the  groove  in  the 
floor  of  the  pulp  chamber,  as  a  rule  the  point  will  find  the  entrance 
to  this  canal  with  but  very  little  difficulty.  These  canals  are  often 
very  minute  and  extremely  difficult  to  open.  For  this  the  Kerr, 
or  Downey,  broaches  are  used,  beginning  with  the  small  ones,  and 
working  very  carefully;  using  little  or  no  force  to  push  them  into 
the  canals,  but  allowing  them  to  work  their  way  easily  as  the 
broach  is  rotated.  The  sodium  and  potassium  preparation  may  be 
used  to  advantage  in  such  cases,  working  it  in  with  a  broach. 
Sodium  dioxide  is  also  used  for  this  purpose,  and  will  at  times  prove 
quite  effective.  Again,  a  50  per  cent,  solution  of  sulphuric  acid 
may  be  of  assistance.  A  little  of  it,  indeed,  may  be  sealed  into  the 
root  and  allowed  to  remain  until  a  subsequent  sitting,  when  it 
frequently  will  have  so  softened  the  contents  of  the  canal  that  the 
broach  will  readily  find  its  way  to  the  end. 

Fig.  21  will  give  a  fair  idea  as  to  the  position  in  which  these 
canals  are  generally  found,  the  large  palatal  canal  c  being  about  in 
the  center  of  the  palatal  root  and  the  anterior  buccal  canal  a  being 
found  very  close  to  the  anterior  buccal  corner.  The  distal  canal  h 
will  be  found  nearly  on  a  line  between  the  anterior  buccal  and  the 
palatal  canal,  or  slightly  distally  to  it,  but  very  rarely  at  right 
angles  with  the  other  canals.  Occasionally,  the  two  buccal  canals 
have  a  common  opening  into  the  pulp  chamber  (Fig.  22),  and  in 
such  cases,  the  entrance  to  the  separate  canals  will  be  found  just 
a  little  below  the  pulp  chamber  floor. 


POSITION  OF   THE  PULP  CANALS  49 

Occasionally,  but  \ery  rarely,  an  upper  first  or  second  molar 
will  have  but  a  single  root.  When  this  is  the  case,  the  canal  will 
be  very  large,  the  pulp  chamber  sloping  from  all  sides  toward  the 
center  of  the  tooth,  and  the  canal  tapering  to  the  apex  (Fig.  23). 

Again  we  may  find  one  of  these  teeth  which  has  two  roots.  When 
this  is  the  case  the  buccal  canal  is  usually  as  large  or  even  larger 
than  the  palatal  canal.  If,  on  opening  the  tooth,  the  instrument 
drops  readily  into  the  buccal  canal,  midway  between  the  mesial 
and  distal  sides  of  the  tooth,  and  if  it  is  very  much  enlarged  through- 
out its  entire  length,  it  is  a  fairly  certain  indication  that  there  are 
no  more  than  two  canals.  If,  on  the  contrary,  this  canal  is  very 
much  constricted,  it  indicates  the  existence  of  another  canal. 


o  oj 
b 

Fig.  21  Fig.  22  Fig.  23  Fig.  2-4  Fig.  25 

Where  the  molar  has  four  roots,  the  two  palatal  canals  will 
generally  be  larger  than  the  two  buccal,  and  one  will  be  almost 
directly  behind  the  other  following  the  line  of  the  arch  (Fig.  24, 
a  and  b),  although  neither  of  them  will  be  as  large  as  where  there 
is  but  a  single  palatal  root.  The  two  buccal  canals  will  be  about 
in  normal  position  (Fig.  24,  c  and  d). 

Locating  the  Pulp  Canals  of  the  First  and  Second  Lower  Molars.— 
Normallx',  the  lower  UKjlars  have  but  two  roots,  almost  invariably, 
however,  there  are  three  distinct  canals  which  must  be  cared  for, 
one  in  the  distal,  and  two  in  the  mesial  roots.  While  in  reality 
there  is  but  a  single  canal  in  this  root,  it  is  so  constricted  between 
the  buccal  and  lingual  openings  that  this  part  of  the  canal  is  almost 
obliterated,  the  s{)ace  between  the  walls  of  the  canal  at  this  point 
being  so  slight  that  there  is,  practically,  no  pulp  tissue  between 
them  (Fig.  25). 

The  distal  canal  r  being  the  one  most  easily  accessible,  is  naturally 
the  one  first  looked  for.  Tiiis  canal  being  nnich  larger  than  those 
in  the  anterior  root,  and  the  position  being  favoral)le,  it  is  readily 
located  and  the  jjnlp  easily  removed. 

The  canal  next  sought  for  is  generally  det('riniiie(|  b.N  the  inclina- 
tion f>f  the  tooth,  if  this  be  excessively  to  the  lingual  it  would 
4 


50 


THE  PULP  CANALS 


Fig.  26 


Fig.  27 


naturally  be  the  lingual  canal  (Fig.  25,  h),  as  this  position  of  the 
tooth  renders  it  more  easy  to  reach.  In  locating  the  canals  in  this 
root,  the  rule  in  regard  to  the  order  in  which  they  are  opened  is 
not  followed  as  closely  as  it  is  in  locating  the  buccal  canals  in  the 
upper  molar.  At  times,  the  buccal  canal  (Fig.  25,  a)  is  more 
quickly  and  easily  located  than  the  lingual. 

Very  frequently  the  distal  slope  of  these  roots  is  such  that  it 
will  be  necessary  to  cut  the  mesial  wall  of  the  tooth  almost  to  the 
gum  line  in  order  that  the  instrument  may  follow 
;  /     the  line  of  either  the  mesial  or  distal  canals  (Fig.  26) . 
The  buccal  canal  of  the  mesial  root  is  the  principal 
offender  in  this  respect,  and  it  is  sometimes  neces- 
sary to  cut  the  mesio-buccal  corner  of  the  tooth 
entirely  away  before  an  entrance  into  the 
canal  can  be  effected. 

The  mesial  canals  are  frequently  so 
constricted  and  tortuous  as  to  render  it 
extremely  difficult  to  open  them  all  the 
way  to  the  apex.  At  times  it  is  necessary 
to  spend  hours,  or  even  days,  toget  these 
canals  properly  opened  and  enlarged,  but  one  of  them,  at  least, 
must  be  opened  all  the  way  to  the  end  of  the  root. 

These  canals  sometimes  diverge  buccally  and  lingually  as  they 
leave  the  pulp  chamber,  and  converge  as  they  approach  the  apex, 
having  a  common  foramen  (Fig.  27). 

If  it  is  practically  impossible  to  entirely  open  but  one  of  these 
canals,  and  the  other  has  been  opened  to  within  a  very  short  dis- 
tance of  the  apex,  the  little  pulp  tissue  remaining  in  this  small 
space  between  the  filling  that  is  to  be  placed  in  the  canal  which  has 
been  opened  to  the  end  of  the  root,  and  the  filling  which  will  be 
placed  as  far  down  in  the  other  canal  as  it  can  be  placed  (Fig.  27,  a 
and  b),  will  hardly  do  any  harm. 

The  canals,  of  course,  must  be  perfectly  sterilized,  particular 
attention  being  paid  to  the  one  which  has  not  been  opened  entirely 
to  the  apex.  The  canal  from  which  the  pulp  has  all  been  removed 
is  filled  very  carefully,  making  certain  that  it  is  filled  all  the  way  to 
the  end.  The  remaining  canal,  which  has  not  been  fully  opened, 
is  saturated  with  a  solution  of  zinc  chloride,  after  which  it  is  filled 
as  far  as  possible,  so  that  only  a  little  thread  of  coagulated  pulp 
tissue  is  left  in  the  root.  This  is  entirely  cut  off  and  isolated  so 
that  the  danger  of  subsequent  trouble  is  very  remote.     If  the 


POSITION  OF   THE  PULP  CANALS  51 

operator  desires,  this  canal  can  be  filled  with  some  mummify- 
ing paste,  but  it  is  only  in  cases  of  this  kind  that  such  a  filling  is 
indicated. 

Occasionally  these  teeth,  as  in  the  case  of  the  upper  first  and 
second  molars,  may  possess  a  greater  or  less  number  of  roots  than 
normal,  and  there  may  be  but  a  single  root  or  there  may  be  several. 
There  is  rarely  any  trouble  in  opening  the  pulp  canal  of  a  single 
rooted  lower  first  or  second  molar,  all  the  way  to  the  end  of  the 
root.  As  in  the  case  of  an  upper  molar,  the  pulp  is  always  very 
large  and  peg-shaped,  so  that  it  is  easily  removed. 

The  third  molars  or  wisdom  teeth  are  especially  lacking  in  uni- 
formit\-  as  to  the  number  of  their  roots;  they  may  have  but  a  single 
root  or  there  may  be  many.  These  roots  frequently  converge  and 
may  be  fused  together  forming  one  large  peg-shaped  root  in  which 
there  may  be  several  canals.  These  canals  are  frequently  so  small 
and  tortuous  as  to  render  it  impossible  to  open  all  of  them  their 
entire  length.  In  such  cases,  the  operator  must  be  satisfied  with 
something  less  than  the  ideal,  so  far  as  filling  them  to  the  end  is 
concerned,  but  should  make  every  effort  to  insure  that  they  are 
at  least  perfectly  sterile. 

It  is  this  uncertainty  in  regard  to  their  condition  which  some- 
times renders  them  unserviceable  as  abutments  for  bridge-work. 
In  such  teeth  it  would  be  impossible  to  give  any  fixed  rule  as  to 
opening  of  the  canals  and  removing  the  pulp,  except  that  the 
pulp  chamber  should  be  fully  opened  so  as  to  give  free  access  to 
all  the  canals  which  it  is  i)<)ssible  to  find. 

Locating  and  Opening  up  the  Pulp  Canals  of  the  Upper  Bicuspids. — 
The  ui)per  first  bicuspid,  is  a  double-rooted  tooth  with  the  canals 
opening  on  the  buccal  and  lingual  side.  The  canals  of  these  roots 
are  sometimes  quite  constricted,  and  require  considerable  time  to 
open  them  all  the  way  to  the  end.  With  a  little  perseverance  and 
the  use  of  the  sodium  and  potassium,  or  sulphuric  acid,  this  can, 
however,  generally  be  accomplished. 

Occasionally  the  root  has  a  very  sharp  curve  near  the  apex. 
Indeed,  it  is  at  times  bent  almost,  if  not  cjuitc,  to  a  right  angle  with 
the  rest  of  the  root.  In  such  cases  it  will  be  impossible  to  remove 
all  of  the  i)ulp  tissue.  As  much  as  possible  is  taken  away  with  the 
broaches,  using  the  sodium  and  i)otassium,  or  the  sodium  dioxide, 
and  then  trust  nnist  be  placed  in  antiseptic;  treatment  to  prevent 
future  trouble.  There  are  times  when  it  may  be  advisable  to  ampu- 
tate these  curved  root  ends,  before  using  the  teeth  as  abutments. 


52 


THE  PULP  CANALS 


The  upper  second  bicuspids  sometimes  show  exactly  the  same 
conditions  as  are  to  be  found  in  the  mesial  root  of  the  lower  molars, 
a  single  root,  but  practically  two  canals,  which  should  be  treated 
in  a  similar  manner  to  those  of  the  lower  molars.  These  canals 
may  be  entirely  separate  and  present  all  the  appearance  of  a  first 
bicuspid,  but  if  they  are  opened  all  the  way  to  the  end,  it  will  be 
found  that  they  unite  at  the  apex  in  one  common  foramen,  and  if 
one  of  the  canals  be  filled,  the  filling  will  be  forced  a  little  distance 
up  into  the  other  canal. 

A  two-rooted  second  bicuspid  occasionally  is  found,  but  this  is 
rare  and  need  not  be  especially  considered,  as  the  treatment  would 
be  the  same  as  for  the  first  bicuspid. 


Fig.  28 


Fig.  29 


Locating  and  Opening  up  the  Pulp  Canals  of  the  Lower  Bicuspids 
and  Anterior  Teeth. — The  lower  bicuspids  have  but  a  single  root, 
and  the  pulp  is  approached  directly  through  the  center  of  the  cusp. 

All  of  the  six  anterior  teeth,  both  upper  and  lower,  are  opened 
from  the  lingual  side,  as  near  the  center  as  possible,  and  it  is  very 
rarely  that  any  trouble  will  be  encountered  in  removing  the  pulp 
and  thoroughly  sterilizing  the  canals. 

X-rays  in  Pulp  Canal  Work. — The  discovery  of  the  Roentgen  rays 
and  the  introduction  of  the  .r-ray  machines  has  been  of  great  value 
to  the  dentist,  and  especially  so  in  pulp-canal  work.  It  has  enabled 
him  to  open  up  the  pulp  canals,  and  to  work  with  almost  absolute 
certainty,  where,  before  its  introduction,  he  had  been  working 
in  the  dark,  and  pulp  canal  operations  were,  to  a  certain  extent, 
mere  guesswork. 

In  all  cases  where  there  is  the  least  uncertainty,  and  in  fact,  in 
treating  any  of  the  teeth,  and  especially  those  having  more  than  a 
single  root,  it  is  advisable  to  have  an  .r-ray  taken  before  beginning 
operations.    The  film  will  show  at  a  glance  the  number,  position, 


POSITION  OF   THE  PULP  CANALS 


53 


and  approximate  length  and  shape  of  the  roots,  and  the  location 
of  the  canals,  thus  enabling  the  operator  to  work  much  more 
quickly  than  he  otherwise  could  (Fig.  28). 

In  difficult  cases,  after  having  opened  and  enlarged  the  canals, 
it  is  an  excellent  plan  to  insert  fine  wires  to  the  depth  to  which  they 
have  been  opened,  and  then  have  another  ;r-ray  taken  to  verify 


Fig.  30. — Wires  in  canals  showing  dis- 
tal canal  perfectly  opened  to  apex,  but 
wire  in  mesial  root  shows  side  of  root 
slightly  penetrated  anterior  to  the 
canal. 


Fig.  31. — Upper  first  Iiicuspid  show- 
ing buccal  canal  entirely  filled  and  pal- 
atal canal  only  upper  third  filled,  the 
balance  of  canal  being  used  to  insert  a 
post  for  a  crown. 


the  work  (Fig.  29).  The  illustration  shows  this  very  clearly,  and 
we  can  appreciate  the  value  of  these  pictures  as  an  aid  in  this 
work.  Many  times,  as  in  Fig.  30,  the  second  picture  will  show  that 
a  canal,  in  which  it  was  thought  that  ^ 
the  work  had  been  perfectly  done,  had 
not  l)een  opened  nearly  to  the  end,  and 
had  it  been  filled  without  carrying  the 
work  further,  might  have  resulted  in 
serious  trouble.  At  times  it  is  well  to 
submit  the  patient  to  a  third  exposure 
before  proceeding  to  fill  the  canals. 
It  is  also  often  advisable  in  difficult 
cases,  and  at  all  times  a  great  satis- 
faction, to  know  whether  our  work 
has  been  perfectly  done,  or  otherwise. 
An  ar-ray  taken  after  the  roots  have 
been  filled  will  readily  show  this 
(Fig.  31). 

The  use  of  the  .r-ray  is  often  a  great  saver  of  time.  At  times  the 
writer  has  worked  for  hours  over  a  tooth,  endeavoring  to  open  up 
certain  canals,  but  lias  failed   until  an  .r-ray  of  the  root  has  been 


Fig.  32.— The  above  r:i(lii)Kiaph 
shows  .a  sharp  turn  biu^kward  of  the 
mesial  root  of  the  lower  first  molar 
and  the  canal  only  partly  (illcd. 
With  the  aid  of  the  dim,  it  was 
possible  to  open  up  both  roots 
easily  and  (|uickly  all  the  way  to 
the  apex. 


54 


THE  PULP  CANALS 


taken.  This  has  shown,  perhaps,  a  curve  in  the  root  which  neces- 
sitated the  cutting  away  of  a  large  portion  of  the  mesial  wall  of  the 
crown  before  it  was  possible  to  get  into  the  canal  more  than  a  short 
distance,  but  after  securing  the  films,  he  has  been  enabled  to  com- 
plete the  work  and  open  the  root  all  the  way  to  the  apex  within  a 
very  short  time  (Fig.  32). 

The  value  of  the  a;-ray  to  the  dentist  cannot  be  overestimated, 
and  those  who  are  taking  advantage  of  it  are  doing  far  better  work 
than  it  would  be  possible  for  them  otherwise  to  do.    A  chap- 
ter on  this  work  has  been  written  by  Dr.  Frederick  K.  Ream, 
of  New  York,  and  will  prove  very  instructive  reading. 

REMOVING  THE  PULP  AND  CLEANSING  THE  PULP 

CANAL. 

The  Donaldson  canal  cleansers,  and  instruments  of  that 
type  are  best  suited  for  the  purpose  of  removing  the  pulp 
where  the  canal  is  sufficiently  large  to  admit  of  their 
entrance  (Fig.  33).  These  broaches  are  barbed  on  all  sides, 
the  barbs  being  cut  around  the  shaft  following  the  direction 
of   the   thread  of  a  right-hand  screw.     Such  instruments 

should  be  used  with  care,  being 
necessarily  very  delicate,  as  in 

]  barbing  them,  the   broach  is 

cut  partially  through,  weaken- 
■  ing  it  to  a  great  extent. 

The  broach  should  be  held 
in  the  fingers  lightly  and 
sholud  never  be  forced.  In 
entering  the  canal  the  broach 
is  rotated  slightly  to  the  right, 
allowing  it  to  be  drawn  into 
the  pulp  tissueand  after  enter- 
jljllj^  llll        ing  to  a  sufficient  depth  may 

I  'Plil  Hi        be  withdrawn  with  the  pulp, 

Fig.  33.— Donaldson's  pulp  canal  cleansers.       Or  a  portion  of   it  adhering  tO 

it.  Never  allow  the  broach  to 
become  jammed.  Keep  touching  lightly,  twisting  it  the  least  bit 
with  each  forward  motion  until  it  catches  a  little,  then  with- 
drawing it,  and  continue  these  movements  until  the  apex  is 
reached.  Should  the  broach  become  jammed,  it  is  released  by 
rotating  carefully  to  the  left. 


REMOVING  PULP  AND  CLEANSING  PULP  CANAL         55 

Where  the  canals  are  very  small,  the  Kerr  or  Downey  broaches 
can  be  used  to  enlarge  the  canals  and  remove  the  pulp,  beginning 
with  the  smaller  broaches  and  working  up  to  the  larger.  While 
these  broaches  are  much  stronger  than  are  the  Donaldson,  care 
must  be  exercised  in  their  use,  as  the  finest  of  them  are  very 
delicate. 

Where  the  canals  are  so  minute  that  trouble  is  experienced  in 
opening  them,  even  with  the  finest  broaches,  the  use  of  sodium 
and  potassium,  or  sodium  dioxide,  is  indicated,  the  soldium  and 
potassium  being  preferred.  A  small  amount  of  the  preparation 
is  carried  to  the  canal  on  the  broach  and  worked  into  it  with 
a  pumping  and  rotating  motion.  This  will  facilitate  matters 
and  tend  to  enlarge  the  canal  slightly,  so  that  the  broach  may 
readily  follow  it. 

At  times  a  drop  of  50  per  cent,  sulphuric  acid  in  the  canal  will 
very  materially  assist  in  the  work,  and  sometimes  if  a  little  of  the 
acid  is  sealed  in  the  canal  and  left  there  until  a  subsequent  visit 
of  the  patient,  it  will  frequently  enable  the  remainder  of  the  canal 
to  be  easily  opened. 

The  openings  from  the  canals  into  the  pulp  chamber  are  generally 
somewhat  constricted,  as  shown  in  Figs.  IS  and  H).  They  should 
be  slightly  enlarged  at  this  point  with  a  Gates-(ilidden  drill.  They 
are  thus  not  only  rendered  easier  of  access  to  the  broach,  l)ut  the 
removal  of  the  ])uli)  is  also  facilitated. 

Instruments  must  be  Perfectly  Sterile. — It  is  to  be  understood  that 
in  all  of  these  operations,  the  instruments  nuist  be  thoroughly 
sterilized  before  using,  and  sometimes  during  the  operation.  This 
is  best  done  in  superheated  steam  or  by  boiling.  The  former  is 
by  far  the  most  thorough  and  efficient  of  any  method  which  can  be 
employed.  Fig.  'M  shows  an  apparatus  for  sterilizing  by  steam. 
The  instruments  are  placed  in  a  tray,  which  is  i)ut  in  a  highly 
heated  cxlinder.  A  little  water  is  then  injected  into  the  cylinder 
and  is  instantl\'  converted  into  steam  of  several  hundred  degrees 
of  heat  and  the  instruments  are  thoroughly  sterilized  in  a  very 
f(nv  moments. 

{''orrnaJin  is  also  a  very  good  sterilizing  agent,  but  it  is  better  to 
use  a  stronger  solution  than  is  generally  employed  for  this  purpose. 
A  solution  of  Formalin  diluted  with  water  alone  will  corrode  the 
instruments  so  as  to  rnin  them  in  a  short  time,  bnt  a  solution  com- 
posed of  one  part  formalin  to  thre(;  parts  of  a  saturated  solution 
of  l)i<;irl»f)nate  of  soda,  may  be  safely  nsed  and  is  very  eiVective. 


56 


THE  PULP  CANALS 


Instruments  placed  in  this  solution  and  left  for  several  days  will 
remain  as  bright  and  clean  as  when  first  put  in. 

The  canal  should  first  be  cleansed  mechanically,  the  sides  being 
thoroughly  scraped  with  the  barbed  cleansers  so  as  to  remove  every 
particle  of  pulp  tissue  that  it  is  possible  to  reach. 

At  all  times,  after  the  pulp  has  been  removed  and  the  canals 
opened,  it  is  well  to  use  the  sodium  and  potassium.  A  platinum 
point  is  best  suited  for  this  purpose,  although  twisted  broaches  of 
the  Keer  or  Downey  type  may  be  used.  A  small  portion  of  the 
sodium  and  potassium  is  taken  up  on  the  instrument,  carried  into 
the  canal  and  worked  in  as  previously  described.  This  will  have 
a  tendency  to  destroy  any  organic  matter  remaining  in  the  canal 
and  render  it  perfectly  sterile. 


Fig.  34 


The  sodium  and  potassium  may  be  used  freely,  but  its  use  must 
not  be  carried  to  an  excess,  as  an  excessive  use  of  this  agent  has  a 
tendency  to  burn  the  life  out  of  the  tooth  structure  and  render 
it  brittle. 

After  the  canals  have  been  opened  to  the  end  of  the  roots,  those 
which  are  very  minute  should  be  enlarged  sufficiently^  to  allow  the 
filling  to  be  properly  inserted.  This  can  be  done  with  the  canal 
files  by  working  them  back  and  forth  in  the  canals  until  they  are 
of  the  desired  size.  The  Donaldson  canal  cleansers  can  be  used, 
but  greater  care  must  be  exercised,  as  they  are  more  easily  broken. 

When  the  canals  are  not  to  be  filled  at  the  time  of  the  removal 
of  the  pulps,  a  small  portion  of  the  sodium  and  potassium  may  be 
sealed  in  the  canals  until  a  subsequent  sitting. 

This  delaying  the  completion  of  the  work,  to  a  subsequent  sitting, 
applies  especiall}^  to  the  multi-rooted  teeth,  where  the  canals  are 


TENDERNESS  AFTER  REMOVAL  OF  THE  PULP  57 

very  minute,  and  much  difficulty  has  been  experienced  in  opening 
them. 

In  the  single-rooted  teeth,  and  also  in  the  larger  canals  of  the 
molars,  where  there  has  been  no  difficulty  in  opening  them  all  the 
way  to  the  end  of  the  root,  the  work  of  devitalizing  and  removing 
the  pulp,  the  cleansing  and  sterilizing  of  the  canals,  and  the  filling 
of  the  root  should  be  completed  at  one  sitting. 

Where  the  work  has  been  delayed,  when  the  patient  returns  and 
the  tooth  is  opened,  the  use  of  the  sodium  and  potassium  is  repeated, 
but  only  a  moderate  quantity  should  be  used.  The  canal  is  then 
thoroughly  waslied  with  a  solution  of  bichloride  of  mercury  and 
peroxide  of  hydrogen,  the  solution  being  composed  of  one  and 
tliree-quarter  grains  of  bichloride  of  mercury  to  two  ounces  of 
peroxide  of  hydrogen.  This  makes  a  bichloride  solution  of  a 
strength  of  about  one  to  five  hundred  and  will  insure  the 
thorough  sterilization  of  the  canals.  This  solution  should  not  be 
used,  however,  until  just  previous  to  filling  the  roots.  If  it  is 
sealed  into  the  canals,  it  is  apt  to  cause  the  patient  pain,  which 
may  continue  for  some  time.  After  having  used  the  bichloride 
solution,  the  canals  are  wiped  out  and  thoroughly  dried  with 
alcohol  preparatory  to  filling. 

Where  the  pulp  has  been  removed  and  the  canals  are  to  be  filled 
at  the  same  sitting,  the  operator  should  proceed  in  the  same  manner, 
using  the  sodium  and  potassium  thoroughly,  and  then  washing  the 
canals  with  the  bichloride  solution  and  drying  them. 

TENDERNESS   OR  SENSITIVENESS  AFTER  THE  REMOVAL  OF 

THE    PULP. 

Tenderness  or  sensitiveness  after  the  removal  of  the  i)ulp  may 
be  due  to  a  minute  portion  of  pulp  tissue  missed  by  the  broaches, 
and  still  adhering  to  the  walls  of  the  canal.  This  is  especially  likely 
to  occur  when  the  canal  is  very  much  flattened,  and  the  puli)  is 
compressed  to  a  knife-like  edge,  generally  on  the  lingual  or 
palatal  sifle  fFig.  3.5).  This  is  most  likely  to  occur  in  the 
cusjiids  and   lower  bicuspid  teeth. 

Occasioriallv,  when  a  patient  returns  to  have  the  pulp 

*'  I'll!  '**' 

canal  filled,  on  a  visit  subs('(|nciit  to  that  on  wliicli  the  i)ulp 
was  removed,  the  tooth  will  be  extreiriely  sensitive.      When  such 
is  the  case,  it  is  (piite   likely  that  a  small   portion  (tf  |)nl|)  tissue 
still  remains  in  the  eanal. 


(!) 


58 


THE  PULP  CANALS 


Sometimes  the  pain  will  cease  at  once  on  thrusting  a  barbed 
broach  quickly  to  the  end  of  the  root  and  twisting  it.  Generally, 
however,  the  sodium  and  potassium  preparation  will  enable  us  to 
remove  this  thread  of  sensitive  tissue. 

In  obstinate  cases  it  may  be  necessary  to  use  a  little  cocain,  or 
local  anesthetic,  pumped  as  far  into  the  canal  as  possible,  before 
being  able  to  remove  the  cause  of  trouble. 

ENLARGING  THE  PULP  CANAL. 

In  enlarging  the  canals  for  the  reception  of  the  post,  none  but  safe- 
ended  instruments  should  be  used.  Instruments  such  as  rose  burs, 
spear-pointed  drills,  fissure  burs  and  those  of  a  similar  character, 
should  never  be  employed  for  this  purpose,  as  they  will  not  follow 
the  canal,  and  there  is  danger  of  perforating  the  sides  of  the  root, 
and  causing  trouble  for  both  the  patient  and  the  operator. 

Determining  the  Length  of  the  Root. — When  enlarging  the  pulp 
canals  it  is  important  to  first  determine  the  exact  length  of  the 
root,  so  as  to  know  just  how  far  it  will  be  safe  to  go  and  how  long 
a  post  can  be  used.  The  Kerr  broaches  or  canal  files,  or  instruments 
of  a  similar  type  are  suitable  for  this  purpose,  beginning  with  a  very 
fine  one,  and  carrying  it  slowly  to  the  apex,  first  cautioning  the 


Fig.  36. — Gates-Glidden  nerve-canal  drills. 


patient  to  give  notice  on  the  first  sensation  of  pain,  or  of  feeling  the 
instrument  at  the  apex.  After  testing  carefully  a  number  of  times 
to  be  certain  that  no  mistake  has  been  made  by  the  patient,  the 
depth  to  which  the  instrument  has  gone  can  be  registered  by  pushing 
a  small  piece  of  rubber  dam  over  the  broach  and  pressing  it  down  on 
the  face  of  the  root,  or  the  incisal  edge  of  the  tooth,  while  the  point 
is  at  the  apex.  This  gives  an  exact  measure  of  its  length.  The  larger 
broaches  can  then  be  used,  but  only  to  within  about  one-eighth 
of  an  inch,  or  a  little  less,  from  the  apex.  Gates-Glidden  drills, 
Fig.  36,  of  different  sizes,  beginning  with  the  smallest  and  ending 
with  the  largest,  can  then  be  used  to  the  same  depth. 

These  latter  instruments  are  safe-ended,  having  a  round,  smooth 
guide  point,  which  will  follow  an  opening,  but  will  not  cut  at  the 


ENLARGING   THE  PULP  CANAL 


59 


end  (Fig.  36,  a).  The  instruments  should  not  be  forced  at  all, 
but  should  be  allowed  to  work  their  own  way  into  the  canal,  with- 
drawing frequently  to  clear  them,  and  just  touching  lightly  until 
the  desired  depth  has  been  reached. 

These  instruments  were  first  made  with  the  shank  tapered,  with 
the  lightest  and  weakest  part  close  to  the  head  (Fig.  36,  b)  and  if 
broken,  only  the  head  of  the  instrument  remained  in  the  canal.  It 
was  very  difficult,  at  times,  indeed,  impossible,  to  remove  them. 
Later  they  have  been  made  tapered  in  the  opi)osite  direction,  so 
that  the  lightest  and  weakest  part  is  far  uj)  on  the  shank,  and  if 
broken  at  this  i)oint  (Fig.  36,  c)  the  part  left  in  the  root  can  be 
removed  with  comparative  ease.  When  pur- 
chasing instruments  it  is  wise  to  see  that  they 
are  of  the  later  ])attern. 

The  Gates-Cilidden  drills  are  followed  with 
reamers  of  suitable  size,  bearing  the  writer's 
name  (P'ig.  37),  enlarging  the  canal  sufficiently 
to  take  a  pin  or  a  tube  of  the  size  desireil. 
These  instruments  are  also  safe-ended,  having 
a  smooth-rounded  guide  point  the  same  as  the 
Gates-Glidden  drills.  They  will  follow  the 
canal  and  enlarge  it,  but  will  not  cut  at  the  end, 
and  in  using  them  there  is  not  the  slightest 
danger,  hardly  a  jjossibility,  with  ordinary  care, 
of  perforating  the  root. 

The  manner  in  which  the  canal  of  a  tooth 
is  enlarged  depends  upon  the  style  of  a  crown 
that  is  to  be  used. 

Enlarging  Pulp  Canals  for  Richmond  Crowns. — Where  a  Uichinond 
crown,  or  a  crown  with  porcelain  facing  and  a,  solid  metal  back  is 
to  be  used,  after  the  canal  has  been  opened,  the  reamer  is  i)artly 
withdrawn  and  sloi)ed  lingually,  enlarging  the  canal  at  the  gingival 
end  of  the  root  in  that  direction  (Fig.  3S,  a  and  h).  The  object  of 
enlarging  the  canal  in  this  maimer  is  to  allow  jjlenty  of  room 
labially,  to  place  tlu;  facing. 

if,  in  any  of  the  six  anterior  teeth,  the  canal  is  sinii)ly  enlarged 
on  its  original  line,  the  facing  will  come  directly  over  the  ()i)ening. 
Tliis  would  necessitate  cutting  the  i)in  olV  finsli  witli  the  floor 
of  the  cap,  in  order  that  the  facing  might  set  flat  on  tUv  floor 
(Fig.  39j.  'i'he  aternative  wonhl  be  to  pursue  another  method. 
This  consists  of  grinding  the  liiignal  side  of  the  fiieing,  toward  the 


Fi(i.  37.— Root- 
reamers. 


60 


THE  PULP  CANALS 


gingival  end,  and  curving  it  outward  so  that  only  a  small  portion 
of  it  rests  on  the  extreme  labial  side  of  the  cap.  The  backing  is  then 
made  to  conform  with  this,  coming  down  flush  with  the  floor,  thus 
making  room  enough  to  engage  the  pin  in  the  solder  (Fig.  40). 

In  the  first  method,  by  grinding  off  the  pin,  and  setting  the  facing 
fiat  on  the  floor  of  the  cap,  the  crown  would  be  rendered  very  weak, 
as  the  only  attachment  the  post  would  have  would  be  to  the  thin 


Fig.  38 


Fig.  39 


Fig.  40 


Fig.  41 


floor  of  the  cap,  and  but  little  force  would  be  necessary  to  tear  it 
away  (Fig.  39).  By  sloping  the  canal  lingually  and  then  giving 
the  post  a  slight  bend  in  that  direction,  it  will  leave  plenty. of  room 
labially  to  place  the  facing  in  its  proper  position  without  weakening 
in  the  least  the  attachment  of  facing  or  post  (Fig,  41). 

The  objection  to  the  second  method,  that  of  grinding  the  facing 
labially,  carrying  the  backing  down  to  the  point  of  contact  with 
the  floor  of  the  cap,  and  filling  in  this  space  with  solder,  is  that  it 


Fig.  42 


Fig.  43 


Fig.  44 


too  often  makes  the  work  conspicuous.  The  mass  of  gold  being 
carried  so  near  to  the  labial  face  of  the  tooth  renders  it  visible. 
It  will  glitter,  or  cast  an  ugly  dark  shadow  between  the  teeth,  and 
be  very  unsightly.  This  is  especially  true  if  the  teeth  are  quite 
fan-shaped,  with  broad  spaces  between  them  near  the  necks  and 
applies  particularly  to  the  upper  six  anterior  teeth  (Fig.  42) .  There 
are  times  when  the  facings  may  be  gound  in  this  manner,  as  in  the 


ENLARGING  THE  PULP  CANAL 


61 


case  of  the  bicuspids,  or  more  rarely,  even  in  the  cuspid,  where  they 
are  broad  at  the  neck,  but  orchnarily  it  is  not  advisable. 

Enlarging  Pulp  Canals  for  an  all  Porcelain  or  Downie  Crown. — Where 
an  all  i)orcehun  crown  or  a  Downie  crown  is  to  l)e  used,  either 
building  up  the  entire  crown  with  porcelain,  or  using  a  facing  and 
building  up  the  lingual  portion  only,  the  canal  is  simply  enlarged 
in  its  original  direction  so  that  the  pin  will  set  directly  in  the  center 
of  the  tooth.  This  applies  especially  to  the  upper  anterior  teeth 
where  there  is  but  little  force  exerted  except  in  an  outward  direc- 
tion. The  reason  for  this  is  as  follows:  Porcelain  is  a  very  fragile 
material  and  its  strength  is  only  in  proportion  to  its  bulk.  By 
having  the  post  in  the  center  of  the  root,  and  cutting  a  groove  on 
the  lingual  side  of  the  facing  between  the  tooth  pins  (Fig.  43),  so 
that  the  post  will  set  in  nearly  flush  with  the  back  of  the  facing, 
it  permits  a  greater  bulk  of  porcelain  lingually  to  the  post,  thus 
giving  increased  strength  to  the  crown  (Fig.  44). 

If  the  post  is  allowed  to  come  lingually,  as  in  the  case  of  a  Rich- 
mond crown,  it  would  permit  of  but  little  porcelain  back  of  it, 
particularly  if  the  bite  was  very  close,  thus  rendering  it  very  much 
weaker  than  it  would  otherwise  be.  This  does  not  apply  so  par- 
ticularh'  to  the  lower  anterior  teeth  as  with  them  the  greater 
pressure  is  inward. 


Fig.  45 


Fig.  4() 


Wlicii  j)lacing  a  Richmond  or  a  porcelain  crown  on  an  upjxT 
first  bicusj)id  root,  it  is  very  rarely  that  there  is  any  necessity  for 
using  more  than  one  of  the  canals  for  the  post  and  the  palatal  canal 
should  always  be  chosen.  In  mastication,  the  force  exerted  on 
these  teeth  is  always  upward  and  outward  (Fig.  45),  consccjuentiy 
if  the  post  is  well  anchored  into  the  |>alatal  root,  there  will  be  no 
necessity  for  a  post  in  the  buccal  root,  for  the  reason  that  the  direc- 
tion of  force  is  such  that  the  crown  will  always  be  forced  tightly 


62  THE  PULP  CANALS 

against  the  root  on  the  buccal  side,  and  the  post  in  the  palatal  canal 
will  bind  it  firmly  to  the  root  at  that  point  (Fig.  46).  The  only 
exception  to  this  is  where  the  teeth  have  extruded  somewhat,  and 
the  roots  are  much  decayed  far  down  under  the  gum.  From  the  fact 
of  their  being  so  short,  it  might  at  times  be  advisable  to  utilize 
both  canals  in  order  to  give  the  necessary  retention, 

FILLING    THE   PULP   CANAL. 

There  are  many  different  methods  and  materials  used  for  filling 
pulp  canals.  Satisfactory  and  permanent  results,  however,  depend 
fully  as  much  on  the  manner  in  which  these  fillings  are  inserted  as 
it  does  on  the  materials  which  are  employed  for  the  purpose. 
Among  these  we  find  gutta-percha  points,  oxychloride  of  zinc,  gold, 
chlora-percha,  paraffin  and  even  wood  points.  It  is  probable  that 
gutta-percha  and  oxychloride  of  zinc  are  more  extensively  used 
than  are  any  of  the  others. 

Gutta-percha  Points. — Of  all  materials,  the  writer  believes  that 
the  very  best  results  are  obtained  from  using  gutta  percha  points. 
He  also  believes  that  a  filling  of  this  material  is  much  more  easily 
inserted,  and  that  it  is  possible  to  carry  the  filling  to  the  extreme 
end  of  a  very  fine  canal  with  a  great  deal  more  certainty  than  can 
be  done  with  any  other  material. 

As  a  preliminary  to  the  operation,  it  is  understood  that  the 
rubber  dam  is  to  be  applied,  if  the  conditions  will  permit,  and  if  not, 
napkins  should  be  used  to  keep  the  mouth  as  dry  as  possible. 

A  point  is  selected  of  a  size  corresponding  to  the  canal  which  is 
to  be  filled,  and  placed  for  a  time  in  the  bichloride  solution  to 
sterilize  it.  It  is  then  dried  on  a  napkin  and  attached  to 
the  end  of  a  canal-plugger  by  heating  the  point  of  the  instru- 
ment. The  canal,  being  thoroughly  cleansed  and  dried  with 
alcohol,  is  slightly  moistened  with  eucalyptus  oil,  carrying  it  into 
the  root  on  a  small  wisp  of  cotton  twisted  around  a  broach,  or 
between  the  points  of  a  pair  of  fine  dressing  pliers.  The  gutta- 
percha point  is  first  dipped  into  the  oil  of  eucalyptus  and  then 
just  the  tip  of  it  into  aristol,  or  iodoform,  after  which  it  is  placed 
in  the  canal  and  worked  into  it  with  a  slight  pumping  motion, 
carrying  it  farther  and  farther,  as  the  oil  softens  it,  until  the  extreme 
apex  is  reached,  which,  in  the  majority  of  cases,  can  be  told  by  the 
patient  wincing.  If  the  point  has  not  become  loosened  from  the 
plugger  by  this  time,  it  can  be  freed  by  rotating  the  plugger  a 


FILLING  THE  PULP  CANAL  63 

little,  after  wliieli  the  point  is  packed  tightly  into  the  end  of  the 
canal. 

It  is  not  objectionable  to  see  the  patient  wince  a  little  during  the 
operation  of  filling  a  pulj)  canal.  In  fact,  it  is  rather  desirable,  as 
it  is  a  very  good,  though  not  an  infallible  indication  that  the  end 
of  the  root  has  been  reached. 

Chloroform  may  be  used  in  place  of  the  eucalyptus  oil,  injecting 
it  into  the  root  and  working  the  point  with  a  pumping  motion  the 
same  as  where  the  oil  is  used.  It  is  not  probable,  however,  that 
it  will  make  as  perfect  a  filling  as  where  the  eucalyptus  oil  has 
been  used.  The  chloroform  evaporates  or  penetrates  the  tooth 
structure  ^'ery  rapidly,  so  that  the  softened  gutta-percha  soon 
becomes  a  sticky  mass  adhering  to  the  side  of  the  canal,  and  has  a 
tendency  to  ])re^'ent  the  point  going  freely  to  the  apex.  Then,  too, 
the  rapid  evaporation  of  the  chloroform  is  liable  to  cause  a  shrinkage 
of  the  gutta-percha,  so  that  after  a  time  it  ceases  to  fully  fill  the 
canal. 

The  eucalyptus  oil  is  much  to  be  preferred  to  chloroform,  as  it 
is  of  a  healing  and  soothing  nature,  besides  possessing  antiseptic 
properties  which  persist  in  the  canal  for  many  years.  It  is  also  a 
slight  sohent  of  gutta-percha,  and  makes  an  excellent  lubricant,  so 
that  the  point  slides  into  the  canal  freely. 

The  canals  are  filled  with  the  gutta-percha  to  within  about  one- 
sixteenth  of  an  inch  of  the  floor  of  the  pulp  chamber.  The  part 
which  remains  unfilled  is  then  carefully  cleansed  with  alcohol  and 
dried  thoroughly,  after  which  it  is  filled  with  oxychloride  of  zinc. 

Where  it  is  intended  to  enlarge  the  canal  in  order  to  insert  a 
post  as  an  attachment  for  a  crown,  the  canal  may  be  enlarged  at 
once,  with  a  reamer,  to  the  desired  size  and  depth,  enlarging  it  to 
within  about  one-eighth  of  an  inch,  or  a  little  less,  from  the  apex, 
before  filling. 

A  very  short  gutta-perdia  point  is  then  used,  dipping 
it  in  eucalyptus  and  aristol,  and  just  filling  the  apex,  i)ack- 
ing  it  tightly  against  the  shoulder  left  by  the  reamer  (Fig. 
47j.     'J'he  canal  is  then  wijx'd  dry  and  the  gutta-percha      j,^^   ^^ 
covered  liglitl\'  with  oxychloride  of  zinc. 

Filling  Pulp  Canals  with  Enlarged  Foramen.-  Where  the  aj)ical 
foranicM  is  very  much  enlarged,  as  it  will  be  in  the  case  of  an  unde- 
vclojx'd  tooth,  gutta-|)ercha  is  the  only  suitable  material  for  filling, 
and  care  must  be  used  so  that  the  filling  is  not  forced  beyond  the 
apex.    The  exact  length  of  the  root  is  first  ascertained  by  passing 


64 


THE  PULP  CANALS 


Fig.  48 


a  hooked  broach  through  the  enlarged  opening  and  marking  the 
length  with  a  small  piece  of  rubber  placed  over  the  broach  (Fig. 
48,  b). 

It  is  always  advisable  to  have  at  hand  a  series  of  different  sized 
canal  pluggers,  from  which  one  is  selected  which  will  pass  into  the 
canal  only  to  within  about  one-eighth  of  an  inch, 
a       b        c      or  a  little  less,  from  the  end  (Fig.  48,  a).     This 
can  be  told  by  placing  it  alongside  of  the  hooked 
broach  used  for  measuring  its  depth.     A  blunt 
gutta  percha  point  is  now  selected,  slightly  larger 
than  the  end  of  the  canal  plugger  and   a  little 
shorter  than  the  distance  from  the  end   of  the 
plugger  to  the  end  of  the  canal  (Fig.  48,  c).    This 
is  attached  to  the  end  of  the  plugger,  and  is  then 
dipped  in  eucalyptus  and  aristol  and  pressed  firmly 
in  place  at  the  end  of  the  root,  the  canal  hav- 
ing been  previously  dried.    The  plugger  is  then 
loosened   by   rotating,    after  which  the  canal  is 
washed  and  dried  w^ith  alcohol  and  the  gutta-percha  is  covered 
over  lightly  with  oxychloride  of  zinc. 

The  diameter  of  the  gutta-percha  point  having  been  somewhat 
greater  than  that  of  the  canal  to  be  filled  and  also  slightly  shorter, 
it  packs  very  tightly  in  place  as  far  as  the  plugger  point  will  carry 
it,  and  at  the  same  time  the  contraction  of  the  canal  elongates  it  a 
little,  so  that  the  apex  is  perfectly  closed.  Then  too,  the  plugger 
being  of  large  size,  renders  it  impossible  for  the  filluig  to  be  forced 
beyond  the  point  desired,  and  through  the  foramen  where  it  might 
act  as  an  irritant. 

A  plugger  of  a  smaller  diameter  than  the  apical  foramen  should 
never  be  used  in  filling  these  canals.  An  accident  or  a  sudden 
movement  of  the  patient  might  cause  the  filling  to  be  forced  through 
.the  end  of  the  root,  with  no  possibility  of  removing  it. 

If  the  entire  length  of  the  canal  is  to  be  filled,  the  operation  will 
be  very  similar  to  the  one  described.  The  size  of  the  foramen  is 
ascertained  with  a  suitable  plugger.  The  plugger  used  for  filling 
should  be  just  large  enough  so  that  it  will  pass  into  the  opening  of 
the  canal  from  the  floor  of  the  pulp  chambers,  not  much  more  than 
one-sixteenth  of  an  inch.  The  size  and  length  of  the  gutta-percha 
point  is  determined  from  these  two  pluggers  and  the  hooked  broach. 
It  is  made  of  a  slightly  larger  diameter  and  a  little  shorter  than  the 
canal.    After  it  has  been  dipped  in  the  eucalyptus  oil,  it  is  packed 


FILLING  THE  PULP  CANAL  65 

tightly  in  place  as  far  as  the  plugger  point  will  carry  it.  The  one- 
sixteenth  of  the  canal  remaining  unfilled,  is  covered  with  oxy chloride 
of  zinc. 

Where  chlora-percha  is  used  as  a  filling,  a  little  iodoform  or 
aristol  should  first  be  put  into  the  canal,  after  which  the  chlora- 
percha  is  pumped  in  with  a  broach,  a  fresh  supply  being  added  as 
the  chloroform  evaporates. 

When  it  is  carried  well  into  the  canal,  a  gutta-percha  point  may 
be  forced  into  it,  but  it  is  questionable  if  this  will  make  as  perfect 
a  filling  as  a  gutta-percha  point,  as  there  is  necessarily  a  much 
greater  shrinkage  where  chloroform  is  used  than  there  can  be  with 
only  a  \'ery  small  portion  of  the  oil  of  eucalyptus. 

Oxychloride  of  zinc  should  never  be  used  for  a  filling  where 
the  foramen  is  very  much  enlarged,  and  it  is  probable  that 
in  all  cases,  the  gutta-percha  point  is  to  be  preferred.  Zinc 
chloride  is  a  strong  irritant,  and  if  a  slight  amount  is  carried  be- 
yond the  apex  and  into  the  tissues,  it  may  set  up  an  inflammation 
difficult  to  control,  causing  considerable  pain  and  discomfort  to 
the  patient. 

On  the  other  hanrl,  gutta-percha  is  an  inert  substance,  and  if  a 
little  is  carried  beyond  the  apex,  the  irritation  caused  by  its  presence 
is  slight,  and  will  soon  pass  away. 

Another  objection  to  the  use  of  oxychloride  of  zinc  as  a  canal 
filling,  especially  in  any  of  the  teeth  anterior  to  the  molars,  is  the 
difficulty  of  opening  the  canals  so  filled  for  the  reception  of  a  post,  if 
at  some  futnre  time  it  should  become  necessary  to  crown  the  roots. 
This  difficulty,  however,  may  be  overcome  to  a  certain  extent,  if 
after  the  canal  has  been  filled  with  the  oxychloride  of  zinc  cement, 
before  it  begins  to  harden,  a  gutta-percha  point  is  inserted  and 
forced  as  far  toward  the  apex  of  the  root  as  possible.  Indeed,  it 
is  a  wise  precaution  to  do  this  in  all  cases,  when  using  oxychloride 
of  zinc  as  a  canal  filling. 

Filling  Pulp  Canals  with  Paraffin. — Paraffin  is  also  advocated  and 
used  by  some  for  filling  pulp  canals.  The  canals  are  thoroughly 
dried  and  a  little  iodoform  or  aristol  is  sifted  into  the  openings  of 
the  canals.  The  paraffin  is  then  carried  into  the  canals  with  a  fine 
heated  broach.  It  is  claimed  that  this  makes  a  good  root  filling, 
especially  in  the  lower  teeth,  but  the  writer  does  not  recommend 
its  u.se." 


66  THE  PULP  CANALS 

TREATMENT    OF   PERFORATED    ROOTS. 

A  perforated  root  is  a  complication  frequently  encountered,  and 
unless  slight  and  favorably  located  it  is  at  times  quite  difficult  for 
the  operator  to  decide  what  is  best  to  do.  If  the  perforation  is 
large;  if  there  has  been  much  mutilation  of  the  root  or  irritation  of 
the  soft  tissues,  or  it  has  been  of  long  standing,  it  may,  perhaps,  be 
best  to  remove  the  tooth  or  root.  Each  case,  hoM^ever,  must  be 
decided  upon  its  own  merits,  with  a  strong  leaning  toward  the 
forceps  in  all  doubtful  cases. 

On  the  other  hand,  if  the  tooth  or  root  is  especially  valuable  to 
the  patient,  and  conditions  are  favorable,  it  is  best  to  make  the 
effort,  as  it  is  sometimes  possible  to  restore  even  a  badly  perforated 
root  to  a  healthy  state  with  a  fair  chance  of  its  remaining  so. 

Where  the  perforation  is  recent,  and  there  has  not  been  much 
mutilation  of  the  tissues,  it  can  nearly  always  be  treated  and 
properly  filled  so  as  to  render  the  tooth  serviceable. 

In  all  of  these  cases  unless  the  perforation  has  been  very  recent 
it  is  quite  likely  that  the  soft  tissues  have  grown  into  the  cavity. 
This  intruding  tissue  must  first  be  removed  by  excision,  or  it  may 
be  cauterized  with  trichloracetic  acid,  carbolic  acid,  or  iodin.  Where 
the  size  of  the  growth  is  not  great,  the  opening  may  be  cleared  by 
packing  the  cavity  tightly  with  dry  absi?rbent  cotton.  This  will 
expand  as  it  becomes  moist,  and  will  force  the  gum  tissue  out. 
At  times  gutta-percha  may  be  used  for  this  purpose,  the  cavity 
being  tightly  packed. 

There  are  different  materials  which  may  be  used  for  closing 
these  perforations,  such  as  gold,  gutta-percha,  oxyphosphate  of 
copper,  thin  platinum  or  tin  foil  burnished  over  the  perforation 
and  then  covered  with  one  of  the  above,  and  lastly,  copper  amalgam. 

In  the  experience  of  the  writer  copper  amalgam  has  proven  to 
be  the  most  satisfactory  material  which  can  be  used  in  such  cases. 
The  tissues  seem  to  take  more  kindly  to  it  than  to  any  of  the  others, 
and  if  the  work  is  done  carefully,  there  will  be  practically  no  irrita- 
tion. Many  times,  where  everything  else  has  been  tried  and  failed, 
copper  amalgam  has  proved  most  effective. 

Manner  of  Treating  Perforated  Pulp  Chambers  or  Canals. — The  parts 
are  first  thoroughly  sterilized  and  then  a  little  adrenalin  chloride 
may  be  left  in  the  cavity  for  a  few  minutes,  to  check  any  hemorrhage 
or  flow  of  serum,  after  which  the  cavity  is  thoroughly  dried  with 
alcohol. 


TREATMENT  OF  PERFORATED  ROOTS  67 

Where  there  is  a  ^•e^y  hirge  perforation  in  the  floor  of  the  pulp 
chamber  it  is  well  to  lay  a  little  piece  of  platinum  in  the  form  of 
a  cross  over  the  opening,  as  in  Fig.  49,  so  as  to  prevent  any  excess 
of  the  amalgam  from  being  forced  through.  This  is  then  covered 
with  the  copper  amalgam,  using  a  broad  faced  burnisher  and  spread- 
ing it  carefully  over  the  floor  of  the  pulp  chani})er,  the  sides  of 
which  have  been  ])reviously  undercut  slightly  so  as  to  hold  it.  The 
mercury  should  be  well  squeezed  out  of  the  amalgam  before  puttmg 
it  into  the  ca\'ity. 


Fig.  49 

The  canals  should  also  be  kept  free  from  the  amalgam.  If  the 
perforation  extends  near  them,  pins,  which  have  been  oiled  or 
wiped  with  vaseline  or  cocoa  butter,  can  be  placed  in  the  entrance 
(jf  the  canals,  and  the  filling  smoothed  into  place,  after  which  the 
pins  may  be  removed,  leaving  the  entrances  to  the  canals  free  (Fig. 
50).  The  copper  amalgam  at  this  stage  being  very  soft,  and  also 
very  slow  setting,  the  teeth  should  be  carefully  i)rotected  and  any 
further  operation  in  the  pulp  chamber  or  canals  should  be  postponed 
to  a  subse(|uent  sitting.  The  amalgam  may  be  covered  lightly 
with  temporary  stopping,  care  being  exercised  not  to  use  pressure 
enough  to  force  any  excess  through  the  perforation. 

Where  the  ])erforation  is  at  the  end  of  the  root,  it  may  be  filled 
with  a  gutta-percha  i)oint,  in  the  manner  described  in  treating  of 
filling  pulp  canals  with  enlarged  foramen,  or  packed  with  coi)i)er 
amalgam,  using  a  large  instrument  which  will  penetrate  the  root 
only  to  within  about  one-eighth  of  an  inch  of  the  apex. 

Where  there  has  been  much  inflammation,  a  dressing  on  cotton, 
comjK)sed  of  one  of  the  essential  oils  and  iodoform  or  aristol  or 
tricresol  and  formalin  may  be  kept  in  the  canal  until  the  soreness 
has  passed  away,  when  the  root  may  be  filled  as  already  described. 
An  excess  of  the  oils  or  tricresol  and  formalin  should  be  avoided, 
or  it  may  act  as  an  irritant.  After  dii)i)ing  the  cotton  in  the  litjuid, 
it  should  be  sciuee/ed  in  the  folds  of  a  napkin  bd'ore  a|)plying. 

Where  the  perforat i(»ii   is  at  the   side  of  the  root,  if   it    be   not 


68  THE  PULP  CANALS 

far  below  the  gum  line,  a  small,  thin,  flat-ended  instrument  can 
often  be  passed  under  the  gum  and  held  to  the  side  of  the  root,  so 
as  to  cover  the  opening.  With  this  in  place,  the  amalgam  can  be 
packed  into  the  perforation  and  against  the  instrument.  When  the 
opening  is  so  located  as  to  be  inaccessible  from  the  outside,  a  trial 
plug  should  be  made  for  the  perforation,  showing  the  size  of  the 
opening  and  also  giving  an  idea  as  to  the  amount  of  material  which 
will  be  necessary  to  fill  it.  For  this  purpose,  a  piece  of  base  plate 
gutta-percha  is  used,  passing  it  into  the  canal,  packing  it  carefully 
into  the  opening  and  forcing  it  through  to  the  outer  wall  of  the 

root.    This  plug  is  then  removed  and  will  give  the 
A    size  and  shape  of  the  perforation  (Fig.  51).    A  little 
w      adrenalin  chloride  may  be  left  in  the  cavity  while 

the  filling  is  being  made  ready. 

A  small  piece  of  copper  amalgam,  slightly  larger 

than  the  trial  plug  is  now  prepared.     The  cavity 

thoroughly  sterilized  and  dried,  and  the  sides  of 
the  opening  grooved  or  slightly  roughened,  so  as  to  hold  the  filling 
in  place.  The  material  is  then  packed  into  place  and  smoothed  over 
carefully,  so  that  no  excess  material  is  forced  through  the  opening 
and  into  the  tissues.    It  is  then  left  to  harden. 

If  it  is  desired  to  use  gutta  percha  to  close  the  perforation,  the 
trial  plug  can  be  sterilized  and  shaped  so  that  it  will  reach  not  quite 
to  the  outer  wall  of  the  root,  leaving  a  slight  excess  on  the  inner 
side.  The  plug  is  then  lightly  fastened  to  the  end  of  the  instrument 
and  placed  in  the  opening  and  packed  flush  with  the  canal  wall. 

It  should  be  remembered  that  if  the  root  is  to  be  banded,  the 
amalgam  should  be  kept  within  bounds  so  that  it  will  be  impossible 
for  it  to  come  in  contact  with  the  band. 

FRACTURED   ROOTS. 

This  is  a  troublesome  complication  and  of  somewhat  frequent 
occurrence.  It  is  often  difficult  to  decide  whether  a  root  which  has 
been  split  can  be  saved  or  should  be  extracted.  The  fracture  of 
a  root  is  often  brought  about  by  placing  upon  it  an  artificial  crown 
without  banding  or  protecting  the  root,  and  more  frequently  occurs 
in  the  incisors  and  bicuspids,  than  in  the  other  roots. 

In  the  majority  of  cases,  where  there  is  a  bad  fracture  of  long 
standing,  and  where  the  broken  parts  are  widely  separated,  it  will 
be  necessary  to  remove  the  root,  but  sometimes  it  can  be  made  to 


FRACTURED  ROOTS  69 

do  good  service,  even  when  it  has  been  spHt  all  the  way  to  the 
apex.  As  an  example  an  upper  central  incisor  may  be  taken 
(Fig.  52).  If  the  fracture  is  recent,  and  the 
parts  are  not  much  separated;  so  that  the  gum 
tissue  has  not  crowded  in  between  the  broken 
parts,  they  can  be  brought  together,  and  by 
crowning  the  root  properly,  it  can  be  made  to 
last  for  a  number  of  years. 

As  a  preliminary,  any  tissue  which  may  have 
worked  in  between  the  separated  parts  should  ^'*^"  ^^  ^^^'  ^^ 
be  carefully  removed  and  the  opening  washed 
out  and  thoroughly  sterilized.  To  facilitate  this,  an  instru- 
ment should  be  placed  in  the  split  and  the  broken  halves  forced 
farther  apart,  and  after  the  cleansing  are  drawn  together.  This  may 
be  done  by  using  a  strong  iron  wire.  The  wire  should  be  heavier 
than  that  used  for  taking  the  measurements  of  the  roots,  being 
about  twent}'-eight  or  thirty  gauge  in  thickness  and  is  placed 
over  the  root  and  forced  under  the  gum,  down  against  the  process 
as  far  as  possible.  At  times  it  may  be  necessary  to  slit  the  gum 
on  the  labial  side  in  order  that  it  may  be  placed  far  up  on  the 
root.  The  wire  is  twisted  tightly  on  the  labial  side  until  the  parts 
are  brought  into  close  contact  (Fig.  53).  After  the  parts  are 
brought  together,  the  excess  of  the  twisted  end  of  the  wire  is  cut 
away  and  the  remainder  pressed  upward  close  to  the  gum  so  that 
the  sharp  end  may  not  injure  the  lip. 

Frequently,  a  strong  clamp  placed  over  the  root  will  assist  very 
materially  in  bringing  the  parts  in  close  contact,  and  the  wire  is 
pas.sed  under  this  and  tightened.  The  root  is  then  very  carefully 
.shaped  and  a  tightly  fitting  band  made  for  it  with  pin  and  floor 
comi)lete.  The  l)and  should  l)e  made  of  heavier  material  tliaii  for 
an  ordinary  crown  and  twenty-eight  gauge  of  coin  gt)ld  is  here 
indicated. 

Tiie  completed  caj)  is  then  j)ut  in  position,  the  impression  taken 
and  the  crown  C()mj)leted.  After  the  crown  has  been  made,  it 
is  cemented  to  th(!  root  aJid  when  the  cement  has  thoroughly 
hardened,  the  wire  is  remo\'ed.  This  renders  the  root  perfectly 
firm,  and  if  the  work  lias  been  skillfully  don<',  it  may  last  for  a  great 
many  years. 

WIktc  there  is  only  a  minor  fractnrc  of  llic  root,  tiic  |)i('c('  which 
is  broken  away  can  be  rcrno\c(l  iind  the  bjind  made  to  coxcr  the 
line  of  frarture. 


70 


THE  PULP  CANALS 


BANDING   ROOTS  WHICH   HAVE   BROKEN   APART    AND 
SEPARATED. 

Cases  are  met  with  where  the  roots  of  broken-down  molar  teeth 
have  separated  from  each  other,  but  are  still,  individually,  long 
and  firmly  set.  If  properly  treated,  many  of  these  may  be  used  to 
assist  in  supporting  a  bridge  as  well  as  though  the  entire  tooth  was 
standing. 

Take  the  case  of  an  upper  molar,  where  the  palatal  root  has 
become  separated  from  the  other  two,  as  in  Fig.  54.    These  roots 


Fig.  54 


Fig.  55 


Fig.  56 


should  be  brought  together.  The  gum,  however,  must  first  be 
crowded  from  between  and  from  around  the  sides  of  the  roots,  so 
that  a  clear  impression  of  the  outline  can  be  obtained. 

The  canal  in  the  palatal  root  and  the  canal  of  one  of  the  buccal 
roots  are  enlarged  as  much  and  as  deeply  as  possible  and  pins 
placed  in  them,  and  an  impression  taken. 

A  model  is  prepared  from  this  and  dried  thoroughly.  It  is 
then  trimmed,  carefully  cutting  down  the  sides  of  the  root  and 


Fig.  58 


Fig.  59 


across-  the  line  of  fracture,  care  being  exercised  not  to  scrape  the 
sides  of  the  roots  in  the  least.  The  plaster  is  then  cut  away  from 
between  the  roots  (Fig.  55),  and  the  two  parts  are  brought  in  con- 
tact in  their  normal  position  and  held  there  by  waxing  or  setting 
in  fresh  plaster  (Fig.  56).  A  band  is  fitted  to  this  plaster  stump, 
carrying  it  well  into  the  depression  where  the  roots  are  constricted 
(Figs.  54  and  57). 


BANDING  ROOTS   WHICH  HAVE  BROKEN  APART         71 

The  pins  having  been  removed  from  the  model,  a  staple  of  heavy 
round  platinized  gold,  or  clasp  wire,  with  a  large  loop  (Fig.  5S),  is 
then  made  and  fitted  in  the  canals,  as  shown  in  the  model,  so  as  to 
go  in  with  a  spring  and  hold  the  parts  tightly  together,  as  in  Fig.  59. 
This  staple  is  then  pressed  still  closer  together  and  is  forced  in  the 
root  in  the  mouth.  The  spring  exerts  a  steady  pressure  and  it 
will  generally  be  found  that  in  a  few  hours  the  parts  have  been 
brought  into  contact.  The  staple  should  be  left  in  position  for  a 
couple  of  days  after  the  j)arts  are  in  contact  so  that  the  roots  may 
become  somewhat  set  in  their  proper  position.  The  staple  is  then 
removed,  the  canals  thoroughly'  cleansed  ancl  the  staple  reset  with 
cement.  The  band  is  then  placed  on  the  stump,  the  impression 
and  articulation  taken  and  the  crown  finished  in  the  usual  manner. 
After  it  has  been  cemented,  providing  the  work  has  been  carefully 
done,  the  tooth  will  be  practically  as  good  as  ever  and  will  last 
for  manv  vears. 


Fig.  62  Fig.  63 

Another  case  which  is  frequently  encountered  is  where  the  two 
roots  of  a  lower  molar  have  become  separated,  at  times,  for  quite 
a  fHstance.  If  they  are  of  good  length  and  firmly  set  they  can  be 
utilized.  If  they  are  standing  far  apart  (Fig.  (iO),  it  may  be  well 
to  crown  the  roots  separately  and  then  build  up  aii>'  form  of  abut- 
ment to  carry  a  })ridge  that  conditions  favor.  If  the  distance  is 
not  very  great,  say,  not  exceeding  one-sixteenth  of  an  inch  at  the 
most,  they  can  be  treated  in  the  same  manner  as  iidvised  for  the 
upper  molar.  If  they  are  standing  well  out  of  the  gum  they  can 
frequently  be  brought  more  cpiickly  together  by  ])laciiig  a  very 
strong  clamj)  (Fig.  OlJ  over  them,  and  leaving  it  for  a  time  (Fig. 
i')2).  This  will  help  to  bring  the  separated  roots  together,  and  after 
they  are  in  contact  they  can  be  held  in  position  with  the  staple  in 
the  mamier  already  described  (Fig.  (VA). 


CHAPTER  V. 

RELATIVE  STRENGTH  OF  THE  TEETH  AS  SUPPORTS 
FOR  BRIDGE-WORK. 

Those  who  do  crown  and  bridge-work  should  have  a  good  under- 
standing as  to  the  relative  strength  of  the  different  teeth,  and  what 
can  be  expected  of  them  as  supports  in  carrying  a  bridge.  (The 
carrying  capacity  of  the  different  teeth  varies  greatly,  and  it  is 
important  to  know,  approximately,  what  may  be  expected  from 
each.) 

For  many  years  the  writer  has  made  a  careful  study  of  this 
subject  with  the  view  of  determining  just  wdiat  may  or  may  not 
be  expected  of  the  different  teeth  when  serving  as  anchorages  for 
bridge-work.  He  has  made  many  observations  under  widely  varied 
conditions,  and  has  arranged  a  table  for  the  upper  and  lower  series. 

Of  course  it  is  understood  that  conditions  may  exist  which  would 
cause  a  variation  in  the  order  as  given,  but  where  the  conditions 
are  normal  the  table  will  be  found  to  be  nearly  correct. 

Teeth  in  the  Upper  Jaw. — The  teeth  which  may  be  considered 
as  first  in  strength  and  endurance  as  abutments  are  the  cuspids. 
These  are  followed  by  the  first  and  second  molars.  It  is  perhaps 
a  question  as  to  which  of  these  teeth,  the  molars  or  the  cuspids, 
form  the  most  permanent  anchorages,  but  it  is  probable  that  the 
balance  is  rather  in  favor  of  the  cuspids.  After  the  first  and  second 
molars  come  the  second  and  first  bicuspids.  It  is  really  difficult  to 
choose  between  these  teeth,  as  under  proper  conditions  each  seems 
to  do  the  work  equally  well,  although,  if  there  is  any  choice,  it  might 
perhaps  be  given  to  the  second  bicuspid. 

Next  in  order  come  the  central  incisors,  then  the  laterals  and 
lastly  the  third  molars  or  wisdom  teeth.  The  third  molars  are 
placed  last  in  the  list  on  account  of  the  uncertainty  regarding  them, 
and  also  their  position  being  so  far  back  in  the  mouth  as  to  ren- 
der them  very  difficult  of  access  in  devitalizing,  treating,  and  in 
preparing  them  for  the  reception  of  the  crowns  and  fitting  of  the 
bands.  At  times  these  teeth  are  large  and  strong  and  well  rooted, 
and  will  serve  as  abutments,  practically,  as  well  as  the  other  molars. 


STRAIN  ON  A  BRIDGE  OCCLUDING  WITH  A   PLATE       73 

lasting  for  a  great  many  years,  but  on  account  of  the  uncertainty 
associated  with  them,  they  are  placed  at  the  end  of  the  list. 

Lower  Series. — The  strength  of  the  lower  series  follows  practically 
the  same  order  as  those  in  the  upper,  with  the  exception  that  here 
the  lateral  and  central  incisors  are  placed  at  the  end  of  the  list. 
The  roots  of  these  teeth  are  very  small  and  frail,  and  they  are  placed 
last,  notwithstanding  the  uncertainty  associated  with  the  third 
molars. 

Form  of  the  Arch. — The  formation  of  the  arch  is  an  important 
factor  in  the  carrying  capacity  of  the  teeth.  A  bridge  which  in 
one  mouth  might  be  of  the  utmost  value  to  the  patient,  in  another, 
where  the  conditions  are  seemingly  the  same,  the  teeth  being 
equally  good,  but  with  a  differently  shaped  arch,  bridge-work 
might  prove  to  be  a  detriment  rather  than  a  benefit. 

Properly  treated,  a  tooth  can  be  made  to  do  far  more  work  than 
it  was  originally  intended  to  do.  One  tooth  may  do  the  work  of 
two  or  even  three,  under  certain  conditions,  but  these  conditions 
must  be  carefully  and  conscientiously  studied.  It  is  impossible 
to  lay  down  any  fixed  rules  governing  this  point,  and  show  just  where 
bridge-work  is  or  is  not  indicated.  In  two  cases,  which  on  first 
seeing  may  seem  to  be  identical,  there  will  be  found  some  point  of 
dift'erence,  such  as  occlusion,  inclination  of  abutments,  etc.,  w^hich 
may  necessitate  the  treating  of  one  case  in  an  entirely  different 
manner  from  the  other. 

Frequently,  a  case  may  be  presented  which  at  first  glance  seems 
ideal  for  this  kind  of  work,  l)ut  on  studying  it  carefully,  will  prove 
to  be  altogether  unsuitable.  On  the  other  hand,  a  case,  which  on 
first  thought  seems  unsuitable,  may,  after  careful  scrutiny,  prove 
to  be  one  of  the  best.  To  sum  up  in  a  few  words,  there  are  no  two 
cases  which  are  exactly  alike  and  each  must  be  carefully  studied 
and  decided  upon  its  own  merits. 

THE  STRAIN   ON  A  BRIDGE  OCCLUDING  WITH  A  PLATE. 

Whether  a  bridge  is  to  occlude  with  natural  teeth,  or  with  arti- 
fi(;ial  teeth  on  a  plate,  may  properly  have  a  deciding  infiuence  when 
coiisiflcring  its  construction. 

If  the  bridge  is  to  occlude  with  teeth  on  a  i)lute  it  can  be  made 
longer,  and  with  weaker  abutments,  than  would  be  safe  were  it  to 
<tcc\\u\('  witli  natural  teeth,  as  the  force  of  mastication  is  far  less 
where  a  plate  is  worn  than  where  the  natural  teeth  are  standing. 


74         RELATIVE  STRENGTH  OF   THE   TEETH 

BRIDGE  SUPPORTS. 

When  and  Where  Bridge-work  is  Indicated. — Although  it  is  im- 
possible to  lay  down  any  fixed  rules  governing  this  work,  there  are 
some  typical  cases  which  are  frequently  presented  that  will  be 
considered. 

Beginning  with  the  simpler  cases,  take  the  anterior  part  of 
the  mouth  where  one  tooth  is  missing,  for  example  an  upper 
lateral,  both  of  the  adjoining  teeth  being  in  perfect  condition. 
Now,  in  the  majority  of  these  cases,  a  small  plate  is  used  to  restore 
the  missing  tooth,  but  the  ideal  fixture  would  be  a  small  bridge 
anchored  to  the  adjoining  teeth. 

In  a  bridge  of  this  kind,  it  is  necessary  that  the  tooth  serving  as 
an  abutment  should  be  devitalized,  and  that  tooth  should  always 
be  the  cuspid.  The  reason  for  this  is  not  that  the  central  is  a  weak 
tooth,  for  it  would  be  amply  strong  to  carry  the  dummy,  but  for 
very  good  reasons  which  will  be  given  later. 

It  is  rarely  that  it  is  necessary  or  advisable  to  cut  oft'  the  crown 
of  this  abutment  tooth,  but  by  devitalizing  it  and  using  an  inlay 
abutment,  we  preserve  the  natural  crown  and  the  bridge  will,  if  the 
work  be  carefully  done,  last  a  long  time. 

There  is  an  inflexible  rule  which  should  be  followed  in  all  cases  of 
restoration  with  bridge-work  whether  it  be  of  a  single  tooth  or  of  a 
longer  series  of  teeth.  It  is  this,  always  have  at  least  two  swirporis  jur 
a  bridge.  Never  trust  to  a  single  tooth  to  carry  the  dummy.  Always 
provide  some  additional  support  at  the  opposite  end  of  the  bridge, 
if  it  has  but  a  single  retaining  abutment,  even  though  it  be  a  slight 
one. 

When  the  two  lateral  incisors  are  missing,  ordinarily  the  two 
centrals  will  safely  carry  the  dummies  restoring  the  lost  teeth,  but 
if  the  teeth  should  seem  weak  or  the  arch  V-shaped,  additional 
support  should  be  had  in  the  way  of  a  light  spur  resting  against  a 
small  gold  filling  or  inlay  on  the  lingual  surface  of  the  cuspids. 
This  will  prevent  the  bridge  from  being  forced  labially. 

Where  the  central  incisors  have  been  lost,  the  laterals  will  serve 
as  abutments.  It  is  best  to  cut  them  off  and  crown  them,  as  these 
teeth  are  generally  too  weak  and  slight  for  inlay  abutments,  but  they 
should  receive  additional  support  from  the  cuspids,  as  in  the  case 
of  the  missing  laterals. 

Where  a  central  and  a  lateral,  both  of  the  same  side,  have  been 
lost,  as  in  Fig.  64,  the  central  and  lateral  of  the  opposite  side  may 


BRIDGE  SUPPORTS 


75 


serve  as  the  main  or  retaining  abntments,  but  they  should  have 
additional  support  from  the  cuspid  in  the  way  of  a  spur  resting  in 
a  pit  or  groove  in  a  gold  filling  or  an  inlay.  In  a  case  of  this  kind, 
the  cuspid  alone  might  serve  as  a  retaining  abutment  with  the  spur 
resting  on  the  lingual  side  of  the  remaining  central. 

Where  the  central  and  lateral  of  opposite  sides  (Fig.  65)  are  to 
be  restored,  the  remaining  central  and  lateral  may  be  used  with 
additional  support  from  the  cuspids,  as  above.  In  either  of  the 
above  cases,  if  the  lateral  and  central  abutments  are  not  very  strong, 


Fig.  64 


Fig.  65 


one  or  at  times  both  of  the  cus])ids  should  be  devitalized  and 
utilized  as  retaining  abutments,  using  inlays  and  pins,  or  if  the 
bridge  be  removable  inlays  with  tubes  and  split  pins. 

Where  all  of  the  incisors  are  missing,  a  lasting  bridge  may  be 
made  by  using  only  the  cuspids  as  abutments,  providing  these  teeth 
stand  well  apart  and  the  bridge  can  be  made  on  nearly  a  straight 
line  with  the  abutments,  or  with  only  a  slight  outward  curve, 
(Fig.  ()()).  Where  the  arch  is  V-shaped  and  narrow,  so  that  when 
in   position    the  center  of    the    bridge    will    extend    outward    far 


Fig.  66 


Fig.  67 


beyond  the  line  of  abutments,  as  in  Fig.  07,  the  leverage  would 
be  so  great,  if  the  cnspids  only  were  used,  as  to  force  the  body  of 
the  bridge  ui)vvard  and  outward,  thus  carrying  the  cuspid  roots 
forward,  making  a  gradually  incrcasiiig  sj)a('e  between  the  upjxT 
and  lower  incisors  and  e\cntu;illy  loosening  the  cnspid  abutnients 
(Fig.  (iSj. 

With  an  ardi  of  this  shape,  it  is  necessary  to  sccnrc  sonic  addi- 
tionaj  supports.  Tliis  can  be  done  by  utilizing  the  first  l)icusj)ids 
and  gJN'ing  tliem  a  broad   otclusal  surface.      This  will  eU'ectually 


76 


RELATIVE  STRENGTH  OF   THE   TEETH 


overcome  the  tendency  of  the  body  of  the  bridge  to  move  upward. 
In  order  to  do  this,  it  would  be  necessary  to  force  the  bicuspid 
abutments  downward,  the  cuspids,  which  are  always  deeply  set, 
serving  as  a  fulcrum,  and  this  would  be  impossible  on  account  of 
their  occlusion  with  the  lower  teeth. 

In  the  case  of  a  full  denture  there  should  be  at  least  four  good 
strong  abutments.     The  two  cuspids  and  a  first  or  second  molar 

on  each  side  of  the  arch  would  form 
an  ideal  case  for  a  minimum  number 
of  anchorages.  A  bridge  of  this  kind 
should  be  made  in  one  piece,  thus 
making  one  side  assist  in  supporting 
the  other. 

Large  Bridges  One  Piece  or  Divided. 
— If,  with  only  the  four  abutments, 
the  bridge  is  made  in  two  parts, 
divided  at  the  median  line,  the  tendency  will  be  for  the  two  halves 
to  be  forced  outward  buccally,  thus  separating  the  parts  and  leav- 
ing an  ever-widening  space  between  the  central  incisors.  If  we 
increase  the  number  of  abutments,  having  the  two  central  roots 
in  position,  then  the  bridge  might  be  made  in  two  sections  divided 
at  the  median  line.  In  a  case  of  this  kind,  however,  all  of  the 
abutments  should  be  made  parallel,  as  they  would  be  if  the  bridge 
was  to  be  made  in  one  piece,  so  that  if  the  parts  ever  showed  a 
tendency  to  separate,  they  could  be  removed  and  connected  by 
soldering,  with  the  certainty  that  they  would  go  easily  into  their 
proper  position  in  the  mouth  after  having  been  united. 


Fig.  68 


Fig.  69 


It  should  be  remembered  that  we  cannot  have  too  many  supports, 
and  that  every  additional  abutment  adds  just  so  much  to  the 
chances  of  long  life  for  the  bridge. 

Another  typical  case  is  where  the  first  bicuspid  and  first  molar 
have  been  lost,  as  in  Fig.  69.  In  this  case,  ordinarily  the  second 
bicuspid  and  second  molar  would  be  sufficient  as  abutments,  unless 
the  bicuspid  had  moved  back  toward  the  second  molar,  so  as  to 
leave  a  much  greater  space  than  could  be  filled  by  a  single  bicuspid 


CONDITIONS  FOR  SUCCESS  IN  CROWN  AND  BRIDGE-WORK    77 

dummy;  in  which  event  the  cuspid  should  be  used  as  an  additional 
supporting  abutment  as  the  increased  leverage  of  the  dummies 
would  be  too  great  a  strain  on  the  bicuspid  abutment,  Fig.  70, 
The  same  plan  should  be  followed  where  the  two  bicuspids  are 
missing  and  the  two  molars  are  used  as  abutments. 

Where  a  single  bicuspid  or  a  single  molar  is  missing,  as  a  rule 
there  need  be  but  a  single  retaining  abutment,  but  the  other  end 
of  the  bridge  should  have  a  support  in  the  way  of  a  spur  resting 
in  a  filling  or  an  inlay. 

^Ye  might  go  on  indefinitely  giving  instances  where  bridge-work 
might  be  used,  but  these  few  typical  cases  will  serve  as  a  guide  for 
further  operations  of  this  character  which  may  be  encountered. 

CONDITIONS  MAKING  FOR  SUCCESS  IN  CROWN  AND 
BRIDGE-WORK. 

The  success  of  crowji  and  bridge-work  depends  entirely  on  the 
preparation  of  the  teeth  and  roots.  By  this  preparation,  it  is  not 
meant  simply  the  mechanical  trimming  for  the  reception  of  the 
bands  or  caps,  but  it  begins  at  the  beginning,  the  devitalization 
of  the  teeth  and  the  cleansing  and  filling  of  the  canals.  If  this 
is  not  properly  done,  bridge-work  can  never  be  a  success. 

A  loose  or  diseased  tooth  does  not  necessarily  preclude  the  idea 
of  using  it  as  an  abutment  for  a  bridge.  There  are  many  times 
where  such  teeth,  by  proper  treatment,  may  be  brought  to  a  per- 
fectly firm  and  health\'  condition,  and  a  tooth  or  root  should  not 
be  sacrificed  as  long  as  there  is  the  slightest  chance  of  bringing  it 
to  such  a  state,  but  we  should  not  decide  definitely  to  use  it  until 
it  is  certain  that  a  cure  has  been  effected. 


CHAPTER  VI. 

TYPICAL    SHAPES    OF   THE    TEETH.    MECHANICAL 

PREPARATION  OF  THE  TEETH  AND  ROOTS 

FOR  THE  RECEPTION  OF  THE  BANDS. 

The  surgical  treatment  of  the  teeth  having  been  properly  carried 
out,  the  success  of  the  work  then  depends  upon  the  mechanical 
preparation  of  the  teeth  and  roots  for  the  reception  of  the  caps  or 
bands.  In  order  to  do  this  properly,  it  is  necessary  that  the  operator 
should  thoroughly  understand  and  be  familiar  with  the  anatomy 
of  the  teeth.  A  careful  study  should  be  made  of  the  shapes  of  the 
different  teeth  as  they  would  appear  if  cut  off  about  one-sixteenth 
of  an  inch  below  the  gum  line.  ■  ^ 

It  is  an  excellent  plan  for  the  beginner  to  take  the  different  teeth 
and  cut  them  off  to  about  one-sixteenth  of  an  inch  beneath  the 
gum  line,  or  grind  them  until  the  contour  is  entirely  removed  to 
about  that  point,  so  that  the  band  can  pass  over  the  stump  and 
fit  the  root  tightly.  He  should  not  confine  his  study  to  a  single 
tooth  of  a  given  character,  but  should  observe  many,  and  note  any 
variation  from  the  typical  shape.  There  is  a  typical  shape  to  all  of 
the  teeth,  and  it  is  rarely  that  this  shape  will  vary,  probably  not  in 
1  per  cent,  of  all  the  cases  encountered. 

All  of  the  teeth  or  roots,  if  properly  prepared,  present  something 
of  an  oval  or  triangular  shape,  being  broad  on  the  buccal  or  labial 
side  and  narrower  on  the  lingual  or  palatal  side.  This  must,  of 
necessity,  be  the  case  in  order  that  they  may  be  accommodated  in 
the  arch.  The  appended  chart.  Fig.  71,  well  illustrates  this  and  will 
give  an  idea  of  their  various  shapes  as  they  would  appear  when 
observed  frorii  the  occlusal  or  incisal  ends  of  the  stumps  or  roots. 

The  cross  sections  are  made  at  the  extreme  overlapping  edge 
of  the  enamel  or  about  one-sixteenth  of  an  inch  beneath  the  gum 
line,  the  distance  to  which  the  band  is  supposed  to  be  carried  on  the 
root, 

TEETH  OF  THE  UPPER  JAW. 

In  making  a  study  of  the  teeth  in  the  upper  jaw,  we  find  that  the 
cuspids  are  nearly  true  ovals,  or  egg-shaped,  being  broad  on  the 
buccal  and  narrower  on  the  lingual  sides. 


TEETH  OF   THE   UPPER  JAW 


79 


The  shape  of  the  hiteral  incisors  is  ahnost  an  exact  reproduction 
of  the  cuspids  but  of  course  being  very  much  smaller. 


Vui.  71 


In  the  first  bicnspid,  while  it  still  preserves  the  same  general  oval 
shape,  it  will  be  seen  that  it  is  innch  broader  buccally  and  linf,nially 
pntportionalely,  than  are  the  cuspids,  the  buccal  and  lin<;ual 
diameter  of  llii.>  tooth   beiu'^  nearl\-   twice  as  <ireat   as  the  mesial 


80  TYPICAL  SHAPES  OF  THE    TEETH 

and  distal.  After  the  contour  has  been  entirely  removed  from  this 
tooth  to  about  one-sixteenth  of  an  inch  below  the  gum  line,  it  will 
be  found  by  following  the  curve  of  the  buccal  and  lingual  sides  of 
the  root  and  completing  the  circle  on  each  of  these  sides,  that  there 
will  be  two  perfect  circles,  the  lingual  being  slightly  smaller  than 
the  other  (Fig.  72). 

The  second  bicuspid  root  is  practically  of  the  same  shape  as  the 
first,  the  only  difference  being  that  the  second  bicuspid  root  will  be 
slightly  smaller  than  the  first,  but  the  proportionate  mesial  distal 
and  buccal  and  palatal  diameters  remain  practically  the  same. 

In  the  first  molars,  this  tjiangular  shape  is  still  preserved,  but  as 
in  the  case  of  the  bicuspid,  the  buccal  and  lingual  diameter  is  usually 


Fig.  72  Fig.  73 

about  twice  as  great  as  the  mesial  and  distal,  being  broader  on  the 
buccal  side,  where  we  have  the  two  buccal  roots,  and  narrower  on  the 
lingual,  where  there  is  but  one.  This  may  vary  at  times,  and  the 
tooth  be  as  broad,  or  even  broader  on  the  lingual  side,  when  there 
is  an  excessively  large  palatal  root  and  the  disto-buccal  root  sets 
well  inside  of  the  arch  between  the  mesio-buccal,  and  palatal  root 
as  in  Fig.  73,  but  this  is  an  abnormality  and  very  rarely  occurs.  It 
will  always  be  found  that  the  distal  root  sets  considerably  farther 
inside  the  arch  than  does  the  mesial,  thus  giving  the  stump  a  more 
distorted  appearance. 

The  second  molar  presents  the  same  general  shape  as  in  the  case 
of  the  first,  but  the  stump  is  proportionately  a  little  shorter  buccally 
and  lingually  than  is  the  first  molar. 

Very  rarely  the  first  or  second  molars  have  but  a  single  root 
and  then  again,  at  times,  they  may  have  four.  In  the  latter  case, 
the  palatal  side  will  nearly  always  be  broader  than  the  buccal,  as 
the  two  palatal  roots  usually  follow  the  curve  of  the  arch  more 
nearly  than  do  the  buccal  roots,  and  stand  side  by  side  mesially 
and  distally,  one  directly  behind  the  other  (Fig.  24). 

With  the  third  molar,  or  wisdom  tooth,  if  it  has  the  normal 

number  of  roots,  it  will  have  the  same  general  shape  as  in  the  other 

two  molars,  but  this  will  be  still  smaller  proportionately,  buccally 

"and  lingually,  than  the  second,  being  more  nearly  round  than  are 


TE^TH  OF   THE  LOWER  JAW  81 

the  others.  However,  the  shape  of  this  tooth  is  subject  to  a  greater 
variation  than  are  any  of  the  others,  as  it  may  have  but  a  single 
root  or  at  times  even  as  many  as  five  or  six. 

The  central  incisors,  have  still  the  same  general  ovoid  form  as  the 
others,  but  somewhat  distorted.  This  root  has  more  the  general 
outline  of  the  molars,  but  is  proportionately  very  much  shorter 
labially  and  lingually,  and  is  decidedly  triangular  in  shape.  If  these 
teeth  are  properly  set  in  the  arch,  there  will  be  a  V-shaped  space 
between  the  two  roots  lingually.  The  distal  sides  of  the  labial  face 
of  these  roots,  as  in  case  of  the  molars,  set  a  little  farther  in  the 
inside  of  the  arch  than  does  the  mesial. 

TEETH  OF  THE  LOWER  JAW. 

In  the  lower  jaw  we  find  the  central  incisors  still  preserving  their 
oval  character,  but  decidedly  different  in  shape  from  the  upper, 
being  proportionately  much  longer  labially  and  lingually  than  are 
the  centrals  in  the  upper.  These  roots  are  very  small  and  as  a 
general  rule  are  of  little  value  as  supports  in  bridge-work. 

The  lateral  incisors  are  practically  of  the  same  shape  and  char- 
acter as  are  the  centrals,  but  somewhat  larger,  and  while  not  of 
particular  value  as  supports  for  a  bridge,  still  they  are  much  better 
than  are  the  centrals.  The  shape  of  both  of  these  roots,  is  often 
very  much  like  that  of  the  upper  second  bicuspids,  and  at  times  the 
labiolingual  diameter  is  nearly  twice  that  of  the  mesial  and  distal. 

The  cuspids,  as  in  the  upper,  are  nearly  true  ovals,  but  the  lingual 
corner  is  generally  much  sharper  than  is  the  case  with  the  upper 
cuspids. 

The  first  and  second  bicuspids  are  also  nearly  true  ovals  and  l)()th 
practically  of  the  same  shape,  the  first  being  slightly  smaller  than 
the  second,  but  the  lingual  side  is  proportionately  broader  and 
rounder  than  are  the  cuspids. 

The  shape  of  the  lower  molars  is  very  different  from  tiiat  of  the 
molars  in  the  upper  jaw,  but  they  still  tend  to  the  oval. 

First  Molars. — This  tooth  is  more  nearly  square,  l)eing 
broad  anrl  nearly  flat  on  the  mesial  side,  the  same  on  the 
buccal  and  lingual,  the  lines  converging  slightly  toward  the 
distal,  while  the  distal  side  is  more  convex  owing  to  the 
difl'erence  in  the  shapes  of  the  roots  (Fig.  74).  The  mesial  root  is 
almost  exactly  the  same  in  character  and  shape  as  the  n|)per  second 
bicuspifl  rf>ot,  the;  buccal  and  lingual  diameter  being  about  twice 
6 


82  TYPICAL  SHAPES  OF   THE   TEETH 

that  of  the  mesial  and  distal,  while  the  distal  root  is  more  rounded 
than  is  the  mesial.  If  there  has  been  a  recession  of  the  tissues 
there  will  be  a  slight  depression  on  the  mesial  side  of  the  stump 
where  the  root  is  constricted,  and  also  on  the  buccal  and  lingual 
sides  where  the  roots  begin  to  bifurcate  (Fig.  74). 

The  second  molar  presents  the  same  general  shape,  but  the  distal 
root  is  smaller,  making  this  tooth  slightly  narrower  proportionately 
on  the  distal  side  than  is  the  first  molar. 

With  the  third  molar,  if  they  have  the  normal  number  of  roots, 
the  distal  root  is  still  smaller,  the  prepared  stump  often  forming  an 
almost  perfect  triangle,  with  the  corners  rounded.  As  is  the  case 
with  the  upper  wisdom  tooth,  however,  the  shape  of  this  tooth 
is  subject  to  more  variation  than  are  the  others,  as  they  may  have 
but  a  single  root  or  they  may  have  several. 

The  foregoing  is  a  fairly  accurate  description  of  the  shapes  which 
the  stumps  of  the  different  teeth  will  present  after  they  have  been 
properly  prepared  for  the  reception  of  bands.  If  we  carry  these 
shapes  in  mind,  we  will  find  that  the  work  of  trimming  will  be  very 
much  simplified.  In  trimming,  we  are  always  working  toward  the 
typical  shape  and  being  familiar  with  these  shapes  will  materially 
aid  us  in  the  work  of  preparation  and  will  also  enable  us  more  readily 
to  detect  any  variation  from  the  typical  formation. 

TRIMMING  OF  THE  TEETH. 

Wherever  bridge-work  is  used,  it  is  necessary  that  the  teeth 
or  roots,  which  are  to  serve  as  abutments,  should  be  reinforced  as 
much  as  possible  in  order  to  give  strength  and  stability  to  the 
abutments,  and  also  to  overcome,  as  far  as  may  be,  the  possibility 


of  their  being  fractured.  In  order  to  accomplish  this  result,  it  is 
essential  that  the  roots  should  be  banded.  To  do  this  properly, 
the  contour  of  the  tooth  must  be  entirely  removed,  so  that  the  band, 
when  it  is  passed  over  the  crown  of  the  tooth,  will  hug  the  neck 
tightly,  and  reduce  the  possibility  of  gingival  irritation  to  a  minimum 


TRIMMING  OF  THE   TEETH  83 

(Fig.  75).  If  this  contour  is  not  removed,  the  band  will  stand  away 
from  the  root,  cut  into  the  tissues  and  set  up  an  irritation  which  may 
eventually  result  in  the  loss  of  the  tooth  (Fig.  76). 

In  all  of  the  teeth  the  bulk  of  the  trimming  will  be  on  the  mesial 
and  distal  surfaces,  the  contour  of  the  crown  being  greatest  at  the 
points  of  contact  with  the  adjoining  teeth,  and  gradually  diminishing 
as  we  approach  to  gum  line,  until  at  a  point  about  one-sixteenth 
of  an  inch  beneath  this  line,  or  at  the  overlapping  junction  of  the 
enamel  with  the  dentin,  it  entirely  disappears. 

Trimming  of  Lower  Molars. — In  taking  up  the  technic  of  the 
preparation  of  the  teeth  for  the  reception  of  the  bands,  the  prepara- 
tion of  the  lower  first  or  second  molar  will  be  first  consitlered. 

Mewed  from  the  buccal  or  lingual  sides,  the  contour  of  these  teeth 
is  very  great.  The  mesial  and  distal  diameter  at  the  point  of  contact 
with  the  adjoining  teeth  is  from  one-third  greater  to,  at  times,  even 
twice  that  which  it  is  at  the  neck,  or  about  one-sixteenth  of  an  inch 


i-iG.   76 

below  the  gum  line,  at  the  point  of  junction  of  the  enamel  with 
the  dentin.  Viewing  them  from  the  occlusal  surface,  they  are 
oblong,  generally  being  slightly  broader  at  the  mesial  side  than  at 
the  distal  side. 

The  teeth  should  be  trimmed  so  that  the  sides  are  very  nearly 
parallel,  being  slightly  larger  at  a  point  about  one-sixteenth  of  an 
inch  beneath  the  gum  line  (Fig.  77).  It  is  very  necessary  that  the 
stumps  should  not  be  made  too  conical,  as  if  this  is  done,  there  will 
be  very  little  hold  for  the  crown  which  is  to  be  placed  on  it  and  after 
being  cemented  it  would  require  but  a  slight  blow  or  strain  to  loosen 
it  (F'ig.  78).  On  the  other  hand,  if  the  sides  are  nearly  parallel, 
a  very  strong  retention  is  obtained  and  it  would  require  a  greater 
strain  than  is  orrlinarily  brought  to  bear  on  the  teeth  to  loosen  the 
cap  from  its  position   (Fig.  79). 

In  order  to  give  the  teeth  the  desired  shape,  it  is  necessary  to 
have  instruments  of  suitable  design,  so  that  the  work  of  preparation 
may  be  performed  easily,  and  at  the  same  time  with  as  little  pain 
and  inconvenience  to  the  patient  as  possible. 


84 


TYPICAL  SHAPES  OF   THE   TEETH 


The  trimming  of  these  teeth  cannot  be  done  with  a  hand-instru- 
ment, as  the  bulk  of  material  which  must  be  removed,  in  order  to 
allow  the  passing  of  the  band,  is  so  great  that  if  sufficient  force  were 
exerted  to  strip  the  enamel  or  contour  from  the  tooth,  it  would  be 
great  enough  to  remove  the  tooth  from  the  socket,  so  that  the 
only  way  to  remove  it  is  by  grinding. 

It  is  impossible  to  prepare  these  teeth  with  a  straight  flat-faced 
wheel,  so  that  they  will  be  parallel  with  an  anterior  abutment,  as 
in  order  to  remove  the  contour  entirely  on  the  mesial  side,  it  is 
would  be  necessary  to  cut  far  back  toward  the  center  of  the  tooth, 


Fig 


thus  giving  it  a  backward  slope  from  the  gum  line  (Fig.  80) .  Further- 
more, to  remove  the  contour  from  the  distal  side  with  a  straight, 
flat-faced  wheel  would  necessitate  cutting  forward  and  into  the  distal 
root,  leaving  a  ledge  which  would  render  the  fitting  of  the  band 


Fig.  81 


extremely  difiicult  (Fig.  81).  This  trimming  is  best  done  with  a 
saucer-shaped  disk,  as  shown  in  the  iflustration  (Fig.  82).  With 
this  the  sides  can  be  reached  from  almost  any  angle,  the  contour 


TRIMMING  OF   THE  TEETH 


85 


easily  removed,  and  at  the  same  time  the  parallelism  with  the 
anterior  abutment  preserved. 

The  wheels  which  have  been  found  most  suitable  in  these  cases 
are  the  Leaming  disks,  or  wheels  of  the  same  design.  These  Learn- 
ing disks  are  made  of  carborundum  and  vulcanite,  are  very  uniform 
in  textiu-e  and  are  much  superior  to  the  ordinary  carborundum 
wheels,  as  they  will  wear  evenly  and  remain  perfectly  round  and  true 
until  thev  are  worn  awav  entirelv  to  the  hubs. 


Fig.  82 


The  disk,  which  is  used  most  frequently,  is  known  as  No.  421, 
(Fig.  82).  This  disk  is  very  thin  and  of  an  equal  thickness  from 
center  to  circumference.  This  disk  is  suitable  only  for  cutting 
on  its  edge  as  it  is  very  thin  and  continued  pressure  on  either  the 
face  or  reverse  side  is  liable  to  break  it  off  at  tlie  hub. 


Fig.  H3. — liiilb  syriiiKP. 

The  wheel  and  tooth  should  be  kept  constantly  flooded  with  cold 
water,  preferal>ly  iced.  This  can  best  be  done  with  a  .syringe  small 
enough  to  be  held  in  the  left  hand,  at  the  same  time  leaving  some 
of  the  fingers  free  to  hold  the  lijjs  or  cheek  out  of  the  way  of  the  wheel. 
A  small  bulb  syrinue  is  most  siiitablc  for  tliis  piirpos(i  (r'ig.  H^). 


TYPICAL  SHAPES  OF  THE  TEETH 


There  are  appliances  made  for  keeping  the  wheels  wet  which  are 
attached  to  the  hand-piece,  the  water  being  carried  through  a 
tube  to  the  wheel  (Fig.  84),  but  generally  these  are  not  as  satis- 
factory as  the  ordinary  syringe;  as  they  are  in  the  way  of  the  operator 
and  do  not  allow  of  a  firm  grasp  on  the  hand-piece.  When  an  assist- 
ant is  employed  at  the  chair,  the  operator  can  hold  the  lip  or  cheeks 
away  with  a  mirror  or  other  suitable  instrument,  while  the  assistant 
drops  the  water. 


Devised  by  Dr.  C.  E.  Edwards. 


The  tooth  is  examined  carefully  with  an  explorer  in  order  to 
determine  the  approximate  amount  of  tooth  structure  which  will 
have  to  be  removed.  The  edge  of  the  wheel  is  then  placed  on  the 
occlusal  surface  at  just  about  the  point  determined  by  the  explorer, 
and  the  bulk  of  the  contour  can  be  removed  in  one  piece  (Fig.  82). 

The  hand-piece  should  be  firmly  held  so  that  it  is  impossible  for 
it  to  escape  from  the  control  of  the  operator.  It  is  grasped  between 
the  thumb,  and  the  first  and  second  finger  of  the  right  hand.  In 
working  in  the  lower  part  of  the  mouth,  the  third  and  fourth  fingers 
are  braced  firmly  against  the  anterior  teeth  in  the  lower  jaw,  as  in 
Figs.  85  and  86.  In  this  manner  the  instrument  is  held  perfectly 
steady,  and  should  it  become  jammed  between  the  teeth,  the  wheel 
might  be  broken,  but  could  hardly  escape  from  the  operator's 
control  so  as  to  injure  the  tongue  or  cheek  of  the  patient. 

By  working  in  this  manner,  the  operator  has  absolute  control 
of  the  instrument  and  the  firm  grasp  will  inspire  his  patient  with 


TRIMMING  OF  THE  TEETH 


87 


confidence  in  his  abilit\-  to  do  the  work  with  the  least  possible 
injury  to  the  soft  tissues. 

If  the  dentist  be  left-handed,  the  method  of  work  just  described 
should  be  reversed. 

Trimming  the  Lower  Molars. — Mesial  Side. — In  trimming  the 
lower  molars,  there  are  three  principal  cuts  to  be  made  (see  Fig.  87). 
The  first,  and  generally  the  greatest,  is  on  the  mesial  side  of  the 
tooth.  The  second  is  on  the  distal  side  while  the  third  is  on  the 
lingual  side.    These  cuts  should  be  made  in  the  order  here  given. 


Fig.  8.5. — Shows  the  position  of  the  hands  and  instruments  in  trimming  the 
teeth  in  the  lower  left  side  of  the  mouth,  while  Fig.  86  shows  the  position  in  working 
on  the  right  side. 

The  explorer  shown  in  the  illustration  (Figs.  S8  and  89),  is  most 
suitable  for  use  while  trimming  the  teeth,  as  it  is  so  shaped  that 
every  part  of  a  tooth  is  easily  accessible  to  it  and  the  sides  of  a  very 
long  tooth  can  be  reached  to,  or  even  beyond,  the  gingival  border. 

Mesial  Side. — In  grinding,  the  hand  should  be  held  very  steady  and 
tli<-  wliccl  must  not  be  forced,  but  should  be  allowed  to  work  its  way 
through  the  tooth  with  little  more  pressure  exerted  than  that  which 


88  TYPICAL  SHAPES  OF   THE   TEETH 

the  weight  of  the  hand-piece  gives  to.  it.  This  is  continued  until 
the  contour  on  the  mesial  side  of  the  tooth  has  been  removed  (Fig. 
90).  If  on  examination  with  the  explorer,  it  is  found  that  not  quite 
enough  of  the  tooth  structure  has  been  taken  away,  and  that  there 
still  remains  a  little  shoulder,  as  shown  in  the  illustration  (Fig.  91), 
the  use  of  another  wheel  is  indicated.    This  wheel  is  known  as  No. 


422  (see  Fig.  91)  and  is  of  the  same  make  as  No.  421.  It  is  saucer- 
shaped,  as  is  the  other,  but  as  seen  by  the  illustration,  that  while  it 
comes  down  to  a  fairly  sharp  edge,  it  thickens  gradually  as  it 
approaches  the  hub,  and  is  made  of  a  coarser  material.  It  is  much 
stronger  and  cuts  more  rapidly  than  does  the  No.  421.  The  wheel 
being  thick  and  strong,  the  face  or  reverse  side  of  it  can  be  used. 


TRIMMING  OF   THE   TEETH 


89 


The  shoulder  left  after  using  the  fine  wheel  should  be  examined  in 
order  to  determine  just  about  how  much  more  material  it  is  necesary 
to  take  away.  The  face  of  this  wheel  is  then  placed  against  the  tooth, 
the  same  angle  being  preserved  as  with  the  first  wheel,  and  the  face 
of  the  tooth  cut  back  until  the  explorer  shows  that  we  have  gone 
the  required  distance  (Fig.  92). 


Fig.  90 


Fig.  S7 


Fio.  88 


Fig.  91 


FiQ.  89 


This  will  leave  a  little  ledge,  because  this  wheel  should  not  be  used 
for  cutting  below  the  gum  line,  as  its  thicker  edge  and  coarser 
material  would  mutilate  the  gum  unnecessarily. 

The  thin  disk,  No.  421  with  which  the  first  cut  was  made  is  then 
used,  placing  the  edge  of  the  wheel  on  the  ledge  and  cutting  to  the 


00  TYPICAL  SHAPES  OF   THE   TEETH 

required  depth  beneath  the  gum  Hue.  The  explorer  is  now  used  and 
sh'ould  pass  freely  under  the  gum,  and  smoothly  along  the  root.  If 
it  is  found  that  it  is  the  least  bit  too  full,  the  cutting  should  be  con- 
tinued until  it  is  perfectly  flush  and  smooth  with  the  side  of  the  root. 

It  should  be  understood  that  to  trim  the  teeth  properly  it  is 
necessary  to  mutilate  the  gum  tissue  more  or  less.  If  the  contour 
is  entirely  removed  it  is  necessary  to  cut  to  a  sufficient  depth 
beneath  the  gum  line  and  the  loss  of  a  little  blood  should  occasion 
no  alarm.  There  is  no  tissue  in  the  body  which  heals  as  quickly 
as  the  gum  tissue.  In  a  perfectly  healthy  mouth,  even  where  the 
gum  has  been  quite  badly  mutilated,  the  tissue  will  be  found 
entirely  healed  in  a  few  days.  It  is  absolutely  essential  in  all  of 
these  operations  that  the  instruments  be  perfectly  sterile. 

By  using  ice-water  freely,  in  fact  to  have  pieces  of  ice  in  the  glass 
from  which  the  water  is  taken  it  will  act  as  a  partial  local  anesthetic 
for  the  time  being,  so  that  the  cutting  beneath  the  gum  can  be  accom- 
plished with  much  less  pain  to  the  patient  than  it  would  be  otherwise. 

Distal  Side. — The  mesial  side  having  been  satisfactorily  finished, 
the  second  principal  cut  in  the  trimming  should  be  undertaken 
(Fig.  87).  This  cut  is  made  with  the  same  wheel  or  disk  as  was 
used  in  trimming  the  mesial  side. 

It  should  be  remembered  that  the  distal  roots  of  these  teeth  are 
more  rounded  than  the  mesial.  If  the  hand-piece  be  held  perfectly 
steady  in  grinding  down  this  side,  owing  to  the  shape  of  the  wheel 
the  distal  surface  of  the  stump  would  be  ground  concave  rather  than 
convex.  This  can  be  overcome  by  giving  the  hand-piece  a  to  and 
fro  sidewise  motion  following  the  outline  of  the  root,  determining 
with  the  explorer  whether  it  has  been  done  accurately.  This  should 
be  carefully  watched,  and  the  grinding  continued,  using  the  same 
motion,  until  the  instrument  shows  that  the  contour  on  this  side 
of  the  tooth  has  been  entirely  removed. 

Trimming  of  the  Lingual  Side.- — ^The  natural  inclination  of  these 
teeth  is  lingually,  as  will  be  seen  in  the  illustration  (Fig.  93),  and 
in  making  this  third  cut  they  should  be  ground  so  that  the  lingual 
side  is  nearly  perpendicular. 

In  removing  the  lingual  contour,  it  is  best  to  stand  on  the  side 
of  the  patient  on  which  the  tooth  to  be  trimmed  is  located.  If  the 
tooth  is  standing  by  itself,  a  thin  fiat  disk  (Fig.  93)  may  be  used, 
and  nearly  the  whole  amount  of  the  contour  removed  with  one  cut, 
starting  from  the  occlusal  surface  in  the  manner  already  described 
in  the  trimming  of  the  mesial  side  (Fig.  93).    The  trimming  of  this 


TRIMMING  OF  THE  TEETH 


91 


side  should  be  carried  well  below  the  gum  line,  perhaps  even  further 
than  on  the  mesial  or  distal  sides. 

A  smaller  wheel  of  a  different  shape  may  also  be  used  for  this 
purpose,  and  also  to  complete  the  trimming,  after  the  bulk  of  the 
contour  has  been  removed.  This  wheel,  one  of  the  Leaming  set, 
is  of  an  inverted  cone-shape  and  known  as  Xo.  500  (Fig.  94). 


Fig.  94 


If  there  is  an  adjoining  tooth,  great  care  must  be  exercised  so 
as  not  to  mutilate  it,  and  in  that  case,  we  would  use  the  reverse 
side  of  the  Xo.  500  throughout  the  trimming  of  this  surface  (Fig. 94). 


Fig.  95 


Fig.  96 


There  are  diamond  disks  made  to  correspond  in  shape  with  these 
wheels,  which  work  beautifully.  The  disk  Xo.  1 ,  Fig.  95,  corre- 
sponding in  shape  to  the  Xo.  500,  can  be  used  wherever  the  Xo. 
oTK)  is  iridicatefi. 

The  disk  Xo.  2,  Fig.  9b,  of  the  shape  of  the  No.  421,  will  take  the 


92  TYPICAL  SHAPES  OF   THE   TEETH 

place  of  the  carborundum  disk  of  that  number  and  also  of  the  No. 
422,  as  it  is  made  of  copper  charged  with  diamond  dust,  there  is 
no  danger  of  the  disk  being  broken  when  using  it  on  its  face  or  on 
the  reverse  side. 

The  initial  cost  of  the  diamond  disks  is  much  greater  than  that  of 
the  carborundum  and  vulcanite,  but  as  they  will  last  a  great  deal 
longer  they  are  perhaps  the  cheapest  to  use  in  the  long  run,  as 
one  of  them  will  probably  outwear  a  dozen  or  more  of  the  others 
and  will  not  break  should  it  become  jammed. 

Buccal  Side. — ^The  three  sides  of  the  tooth  having  now  been 
completed,  there  remains  the  buccal  side  to  be  trimmed. 

As  will  be  seen  from  the  illustration  (Figs.  93  and  94)  when  the 
lingual  contour  has  been  removed  so  that  this  side  of  the  tooth  is 
nearly  perpendicular,  there  is  very  little  tooth  structure  to  be  re- 
moved from  the  buccal  side  and  at  times,  if  the  lingual  inclination 
of  the  tooth  is  excessive,  there  may  be  nothing  at  all.  The  little  that 
may  have  to  be  removed  can  be  taken  away  with  the  reverse  side 
of  the  inverted  cone.  No.  500.  It  is  most  easily  reached  from  the 
opposite  side  of  the  mouth,  grinding  away  a  little  at  a  time,  using 
great  care  not  to  cut  too  much,  as  should  this  happen  it  will  leave  a 
shoulder  or  ledge  under  the  gum  over  which  the  band  must  pass, 
thus  making  the  fitting  of  the  band  a  very  difficult  operation.  It 
will  be  found  necessary  to  remove  a  little  more  structure  toward 
the  distobuccal  side,  as  the  buccolingual  diameter  of  the  distal 
root  is  somewhat  less  than  that  of  the  mesial. 


Fig.  97 


At  times,  where  the  mouth  is  large  or  the  cheeks  are  very  flexible 
and  can  be  drawn  well  back,  the  trimming  of  this  side  of  the  tooth 
can  be  done  with  the  flat  face  of  the  No.  500  wheel  (Fig.  97),  or 
the  face  of  a  small  flat  disk,  working  from  the  side  of  the  mouth 


TRIMMING  OF  THE  TEETH  93 

on  which  the  tooth  is  located  (Fig.  98),  using,  of  course,  extreme 
care  to  protect  the  adjoining  teeth. 

The  trimming  of  the  four  sides  of  the  tooth  having  been  satis- 
factorily completed,  it  will  be  found  that  the  stump  is  nearly  square, 
being  slightly  narrower  on  the  distal  side  than  on  the  mesial  and  it 
should  also  be  slightly  conical,  being  a  little  larger  just  below  the  gum 
line.    The  operation  is  completed  with  the  rounding  of  the  corners. 


Fig.  98 

The  mesio-lingual  corner  can  be  reached  by  using  the  No.  421 
disk  or  the  diamond  disk  corresponding  to  that  number,  working 
from  the  opposite  side  of  the  mouth  and  giving  a  rotary  or  swinging 
motion  to  the  hand-piece,  being  careful  not  to  cut  too  deeply  into 
the  stump  so  as  to  leave  a  ledge. 

The  mesio-buccal  corner  can  be  reached  with  the  same  wheel 
or  with  the  face  of  a  small  flat  disk,  using  the  rotary  motion  and 
carefully  following  the  curve  of  the  root  at  that  point. 

In  trimming  the  distal  corners,  if  the  tooth  is  standing  alone, 
they  can  be  easily  rounded  by  using  the  reverse  side  of  the  No.  500 
wheel  and  giving  jt  a  rotary  motion  sweeping  around  the  corners 
from  side  to  side.  If  there  is  a  tooth  adjoining  the  one  which  is 
being  trimmed,  it  will  be  necessary  to  use  more  care  in  grinding. 
A  part  of  this  corner  contour  can  be  removed  by  using  the  reverse 
side  of  the  inverted  cone,  going  as  nearly  to  the  gum  line  as  possible 
without  cutting  the  adjoining  tooth.  After  the  operator  has  taken 
away  all  that  he  can  with  the  disk,  it  will  be  necessary  to  remove 
aii\-  corners  or  points  remaining  with  scalers,  or  other  suitable 
hand-instrument. 

The  rjiamond  disk  corresponding  to  No.  500  can  be  mounted 
on  a  suitable  mandrel  with  the  face  or  concave  side  of  the  disk 
outward,  and  if  used  in  the  right-angle  hand-piece,  the  distal  cor- 
ners can  be  finished  to  a  sufncicnt  depth  beneath  the  gum  line,  so 
that  there  will  be  no  necessity  for  using  the  hand-instrument. 


94 


TYPICAL  SHAPES  OF   THE   TEETH 


Very  coarse  emery  cloth  disks  will  be  found  to  be  a  great  help 
in  rounding  and  finishing  the  distal  corners  of  these  teeth,  after 
they  have  been  rovighed  down  with  the  carborundum  or  diamond 
disks.  These  are  also  especially  useful  where  there  is  an  adjoining 
tooth  standing  distally  to  the  one  which  is  being  prepared.  Their 
flexibility  renders  it  possible  to  follow  the  rounded  corners  of  the 
roots  and  at  the  same  time,  as  they  are  safe-sided,  there  is  no 
possibility  of  injuring  the  face  of  the  tooth  behind  it. 

Where  there  is  a  very  great  forward  inclination  of  the  molar, 
as  is  so  frequently  the  case,  where  teeth  anterior  to  it  have  been 
lost  for  some  time,  as  in  Fig.  99,  there  will  be  little  or  no  cutting 


Fig.  99 


necessary  on  the  distal  side  of  the  tooth.  All  of  the  trimming, 
will  be  on  the  mesial  side.  The  tilting  of  the  tooth  so  far  forward 
will  allow  of  the  band  being  passed  perpendicularly  over  the  crown 
of  the  tooth,  clearing  the  enamel  on  the  distal  surface  and  striking 
the  neck  of  the  tooth  beneath  the  gum  line,  as  in  Fig.  99. 

The  same  wheel  should  be  used  for  grinding  the  mesial  surface 
of  the  tilted  tooth,  as  would  be  used  were  the  tooth  to  stand  in 
normal  position.  In  such  cases  it  is  necessary  to  start  far  back  to 
or  beyond  the  center  of  the  tooth  and  cut  well  below  the  gum  line 
on  the  mesial  side,  even  farther  than  it  would  be,  were  the  tooth 
standing  upright  so  that  if  the  band  were  the  fraction  of  an  inch 
longer  than  necessary  it  would  not  pass  beyond  the  trimmed  side 
of  the  root  and  leave  a  sharp  edge  cutting  into  the  tissues,  as  the 


TRIMMING  OF  THE  TEETH 


95 


inclination  of  the  root  is  such  that  there  would  be  a  very  decided 
overhangino;  ledge  at  any  depth  on  the  root  to  which  we  might 
grind  (see  Fig.  99). 


Fig.  100. — Show.s  the  position  of  the  small  cup-shaped  disk  in  trimming  the  distal 
side  of  the  lower  bicuspids  or  molars. 


The  buccal  and  lingual  surfaces  of  the  tooth  are  trimmed  in  the 
manner  already  described,  using  the  same  instruments  as  where 
the  tooth  stands  in  normal  position. 

It  should  be  remembered  that  it  is  better  to  oxer- 
trim  a  tooth  than  to  undertrim  it.  If  too  much  of 
the  contour  is  removed,  so  as  to  leave  a  ledge  beneath 
the  gum,  so  that  the  band  cannot  pass  over  it,  the 
band  can  rest  on  this  Icflge  and  do  very  little  harm 
(Fig.  101);  whereas,  if  undertrimmed,  the  band  will 
stand  away  from  the  neck  of  the  tooth  below  the 
gingival  margin  and  with  the  ragged  line  of  cement  may  set  up 
an   irritation   which  will  c\entuallv  result  in  the  loss  of  the  tooth. 


Fid.  101 


96 


TYPICAL  SHAPES  OF   THE   TEETH 


Lower  Bicuspids. — In  trimming  the  bicuspids,  the  same  methods 
and  wheels  may  be  used  as  in  trimming  the  molars,  using  the  edge, 
face  and  reverse  side  of  the  wheels.  The  mesial  and  distal  contour 
of  these  teeth  may  often  be  removed  in  one  piece,  as  in  the  case  of 
the  molars;  but  it  frequently  happens  that  the  contour  is  not 
sufficient  to  allow  of  this.  In  such  cases  the  operator  should  cut 
down  between  the  teeth  carefulh'  and  remove  the  contour  verv 


Fig.  102. — Shows  the  manner  of  using  the  small  cup-shaped  diamond  disk  in  the 
right  angle  hand-piece  in  trimming  the  buccal  side  of  the  bicuspids  and  molars. 


gradually,  using  the  Xo.  421  disk.  The  No.  500  can  be  used  for 
the  lingual  and  buccal  sides.  The  greater  amount  of  contour 
here,  as  in  the  case  of  the  molars,  is  on  the  lingual  side,  but 
proportionately  not  so  great  as  in  the  case  of  the  molars. 

The  mesio-lingual  corners  of  the  lower  bicuspids  are  the  most 
difficult  to  reach,  and  in  many  instances  it  may  be  necessarj^  to 
use  a  scaler  to  remove  the  tooth-structure  at  these  points  which 
has  been  left  by  the  wheel.  However,  the  diamond  disk  corre- 
sponding to  the  No.  500  used  in  the  right  angle,  will  very  materially 
assist  in  the  operation,  held  in  the  same  manner  as  in  Fig.  102. 


TRIMMING  OF  THE  TEETH 


97 


The  mesio-buccal  comers  can  be  best  rounded  by  using  the  face 
of  ven  thin,  small  flat  disks,  and  giving  the  hand-piece  a  rotary 
motion.  The  trimming  of  the  distal  comers  should  be  done  the 
same  as  in  the  molars,  using  the  reverse  side  of  the  X(j.  .'>(X)  wheel 
and  rotating  to  follow  the  cur\'e  of  the  rrxjt.  In  case  there  is  an 
adjoining  t(x>th,  the  scalers  or  the  inverted  cone  diamond  disk 
may  be  used  in  the  right  angle. 


Flo.  lO'J. — .Shows  the  same  instruincnt  in  the  right  angle  trimniiug  the  lingual  tade 
of  the  lower  hicur/sidi;. 


The  Upper  Molars. — The  shape  of  the  upjx-r  molars  is  very 
different  from  that  of  the  lower  molars,  although  as  in  the  case 
of  the  lower  molars,  the  greatest  amount  of  t(xjth  stmcture  to  be 
removed  is  from  the  mesial  and  distal  surfaces. 

The  cTowns  of  the  upper  molars,  viewed  from  the  occlu.sal  surface, 
are  diamond-sha[)efl,  the  greatest  diameter  Ix-ing  from  the  anterior 
buccal  comer  to  the  j>osterior  palatal  (Fig.  JfM;.  The  same  wheels 
may  be  u.sed  in  their  preparation  as  were  used  in  the  preparation 
of  the  lower  molars. 

7 


98 


TYPICAL  SHAPES  OF   THE   TEETH 


As  in  trimming  the  lower  molars,  there  are  three  principal  cuts 
to  be  made,  mesial,  distal  and  buccal  (Fig.  105). 


A.B. 


Fig.  104 


Fig.  105 


Mesial  Side. — The  first  cut  is  on  the  mesial  side  of  the  tooth, 
and  the  bulk  of  the  contour  will  be  found  at  this  point,  being  slightly 
greater  than  that  on  the  distal  side.    The  first  cut  should  be  made 


Fig.  106 


with  the  No.  421  carborundum  or  with  the  diamond  disk  of  the  same 
shape.  The  bulk  of  the  contour  can  be  removed  with  a  single  cut. 
In  trimming  the  right  upper  molars,  the  third  and  fourth  fingers 
are  braced  on  the  lower  anterior  teeth  in  the  manner  shown  in  the 
illustration  (Fig.  106). 


TRIMMING  OF  THE  TEETH 


99 


In  grinding  the  left  npper  molars,  the  third  and  fourth  fingers 
are  braced  on  the  lingual  surfaces  of  the  upper  anterior  teeth  (see 
Fig.  107). 

If  an  examination  shows  that  a  sufficient  amount  has  not  been 
removed,  wheels  of  the  same  character  can  be  used  as  on  the 
lower  molars,  cutting  back  for  a  distance  at  the  gum  line  with 
the  Xo.  422  or  diamond  disk,  and  finishing  with  the  No.  421. 


Fk;.  107 

Distal  Side.— The  distal  side  of  the  ui)i)er  molars,  unlike  that 
of  the  lower  molars,  is  nearly  flat.  The  contour  on  this  surface 
can  be  removed  with  the  No.  421,  or  the  diamond  disk,  rotating 
the  hand-piece  slightly  from  side  to  side,  but  not  so  much  as  in  the 
case  of  the  lower  molars. 

If  the  tooth  has  extruded  or  the  gum  has  receded  around  the 
neck,  it  will  generally  be  found  neces.sary  to  groove  this  surface 
slightly  miflway  between  the  buccal  and  palatal  sides,  in  order 
to  allow  the  band  to  be  bent  in  at  this  place,  so  that  it  will  hug  the 
root  at  the  f)oint  where  the  roots  begin  to  bifurcaU'. 


100 


TYPICAL  SHAPES  OF   THE   TEETH 


'  Disto-buccal  Side. — The  third  principal  cut  will  be  on  the  disto- 
buccal  corner.  The  distal  root,  setting  further  inside  the  arch 
than  the  mesial,  the  contour  is  consequently  greater  at  that  point. 
The  removal  of  the  contour  from  the  distobuccal  side  may  be 
accomplished  with  the  No.  500  or  diamond  disk,  using  the  reverse 


Fig.  108.- 


-Shows  the  manner  of  using  the  small  diamond  disk  in  the  right  angle 
hand-piece  in  making  this  cut. 


side  and  working  from  the  opposite  side  of  the  mouth,  giving  a  slight 
rotary  motion  to  the  hand-piece,  or  with  the  diamond  disk  used 
in  the  right  angle  hand-piece,  care  being  used  not  to  cut  too  deeply 
(Fig.  108).  _  .  _ 

Mesio-huccal  Side. — On  the  mesio-buccal  corner  it  will  be  found 
that  there  is  very  little,  and  at  times  nothing  at  all  to  be  removed, 
as  frequently  there  is  practically  no  contour  at  this  point,  the  root 


TRIMMING  OF  THE  TEETH  101 

at  the  gingiva  being  nearly  flush  with  the  crown  of  the  tooth.    This 

necessitates  only  the  rounding  oft'  of  the  sharp  corner,  which  can  be 

done  with  the  face  of  a  thin  flat  disk,  rotating  from  side  to  side,  using 

care  not  to  cut  into  the  root  so  as  to  leave  a  ledge,  as  a  ledge  at  this 

point  would  render  the  fitting  of  the  band  much  more  difficult. 

Palatal  Side. — On  the  palatal  side  it  will  also  be  found  that  there 

is  very  little  contour  (Fig.  109)  and  that  it  can  be  removed  with 

the   reverse   side  of  the   No.  500  wheel  or  diamond 

disk,  working  from  the  side  of  the  mouth  on  which 

the  tooth  is  located, and  rotating  to  follow  the  curve 

of  the  palatal  root 

The  corners  mav  be  rounded  with  the  wheels  of  the 

1  "  111  1  •  ^^^-  1*^9 

same  character  as  were  used  on  the  lower  molars,  usmg 

the  No.  421  or  diamond  disk  for  the  mesio-palatal,  with  the  rotary 

motion,  and  the  reverse  side  of  the  No.  500  for  the  distal  corners. 

The  emery  cloth  disk  will  also  be  found  useful  in  rounding  and 

smoothing  the  distal  surfaces  and  corners. 

Upper  Bicuspids. — The  bicuspids  of  the  upper  jaw,  wherever  a 
shell  crown  is  indicated,  which  is  rarely,  are  prepared  in  the  same 
manner  as  are  those  of  the  lower,  the  same  character  of  wheels, 
being  used.  The  corners  of  the  upper  bicuspids  are  much  easier 
to  get  at  and  trim  than  are  those  of  the  lower  jaw,  and  the  bulk 
of  the  tooth  structure  left  at  these  points  by  the  wheel  can 
generally  be  easily  removed  with  a  hand  instrument. 

In  cutting  oft  the  occlusal  surface,  enough  of  the  tooth  structure 
should  be  removed  to  allow  of  the  placing  of  a  thick  solid  cusp. 
Usually  there  should  be  not  less  than  one-sixteenth  of  an  inch 
between  the  top  of  the  stump  and  the  occluding  teeth.  This  can 
readily  be  ground  away  with  a  square-edged  carborundum  or  corun- 
dum wheel.  The  corners  at  the  occlusal  surface  should  be  rounded 
slightly  and  smoothed  so  as  to  prevent  their  cutting  the  tongue  or 
cheek. 

If,  for  any  reason,  after  the  teeth  have  been  prepared  and  ready 
for  the  impression,  the  bridge  cannot  be  placed  in  the  mouth  for 
some  weeks,  as  would  be  the  case  if  the  patient  were  leaving  the 
city  for  a  time,  it  would  be  better  to  leave  the  occlusal  surfaces 
of  the  teeth  intact.  The  bands  are  placed  in  position,  and  the 
impression  taken. 

The  models  are  then  prej)ared  and  after  the  bands  have  been 
removed,  the  occlusal  surfaces  of  the  abutment  stumps  on  the 
models  are  cut  away  to  a  sufficient  depth. 


102 


TYPICAL  SHAPES  OF   THE   TEETH 


The  bridge  is  then  completed,  and  when  the  patient  returns, 
before  undertaking  to  place  the  bridge  in  the  mouth,  the  occlusal 
surfaces  of  the  stumps  are  ground  away  to  a  depth  corresponding 
to  that  which  has  been  removed  from  the  model. 

It  very  frequently  happens,  where  the  teeth  have  been  trimmed 
and  the  occlusal  surfaces  ground  away,  that  the  irritation  neces- 
sarily attending  their  shaping  will  cause  these  stumps  to  elongate 
very  rapidly,  or  shift  their  position,  so  that  if  several  weeks  have 
elapsed  between  the  taking  of  the  impression  and  the  placing  of  the 
bridge  they  may  have  extruded  so  far  as  to  be  in  contact  with  the 
occluding  teeth.  This  would  necessitate  the  further  grinding  of 
the  occlusal  surfaces,  with  the  result  that,  from  the  necessity  of 
the  band  passing  so  much  farther  on  the  stump  than  it  did  originally, 
the  fit  at  the  gingival  end  might  be  impaired  or  entirely  destroyed. 

By  leaving  the  cusps  intact,  however,  the  danger  of  the  teeth 
elongating  is  entirely  overcome,  and  at  the  same  time,  the  cusps 
interlocking  with  their  antagonists,  the  teeth  are  held  in  their 
original  position  and  prevented  from  shifting, 

Trimming  the  Anterior  Teeth. — In  the  preparation  of  the  ante- 
rior teeth  the  work  should  be  done  almost  entirely  with  hand 
instruments. 


Fig.  110 


Fig.  Ill 


Fig.  112 


Fig.  H: 


When  trimming  these  teeth,  the  stump  should  be  left  standing 
out  of  the  gum  for  from  one  thirty-second  to  one-sixteenth  of  an 
inch,  until  after  the  contour  has  been  entirely  removed,  and  the 
band  has  been  fitted  (Fig.  110).    The  reason  for  this  is  as  follows: 

If  the  root  be  cut  at  once  below  the  gum  line,  as  it  will  be  even- 
tually, in  order  to  hide  the  band  when  the  crown  has  been  completed 
and  put  in  place,  the  gum  will  crowd  over  the  face  of  the  root 
(Fig.  HI).  This,  and  the  excessive  bleeding  which  is  sure  to 
occur,  will  interfere  with  the  vision  and  render  the  operation  of 
trimming  much  more  difficult  for  the  operator  and  decidedly  more 


TRIMMING  OF  THE  TEETH 


103 


painful  for  the  patient.  The  taking  of  the  measurement  of  the 
root  is  rendered  much  more  difficult  and  at  times  practically 
impossible,  especially  if  there  has  been  a  great  deal  of  recession 
of  the  gum  on  the  labial  side. 

The  difficulty  of  fitting  the  band  is  greatly  increased,  as  each  time 
the  band  is  placed  over  the  stump,  it  is  necessary  to  crowd  the  gum 


Fig,  114 


Fig.  115. — Enamel  scaler. 


away  in  order  to  place  it,  so  that  on  the  whole  it  is  \ery  disagreeable 
and  in  (satisfactory  to  both  patient  and  operator. 

Where  the  stump  is  left  extending  out  of  the  gum,  it  serves  as  a 
guide  for  the  instrument  in  trimming  and  enables  the  operator 
to  .see  much  more  clearly  just  what  he  is  doing.  It  also  serves  as  a 
guide  in  taking  the  measurement  and  in  fitting  the  band  by  keep- 
ing the  gum  away,  and  enabling  the  fitting  to  be  done  better  and 
inudi  more  quickly,  and  with  far  less  pain  to  the  patient. 


104 


TYPICAL  SHAPES  OF   THE   TEETH 


After  the  band  has  been  fitted,  it  may  be  removed  and  the  stump 
cut  to  any  desired  depth  below  the  gum  hne,  after  which  the  band 
can  be  replaced  on  the  root  and  scribed  around  on  the  inside  at 
the  top  of  the  stump,  so  that  it  may  be  trimmed  to  the  proper 
length. 

The  maximum  diameter  of  the  root  is  at  the  point  of  junction 
of  the  enamel  with  the  root,  and  this  diameter  generally  continues 


Fig.   116.- 


-Shows  the  trimming  of  the  lingual,  mesial,  and  distal  sides  of  the  right 
cuspid  root. 


about  the  same  for  from  one-sixteenth  to  one-eighth  of  an  inch 
below  the  enamel  before  the  root  begins  to  taper  (Fig.  1 12). 

If  this  enamel  is  entirely  removed,  it  will  be  found  that  the  root 
is  of  about  the  proper  shape  for  the  reception  of  the  band  so  that 
it  will  hug  the  root  tightly  (Fig.  113)  unless  there  has  been  an 
excessive  recession  of  the  gum,  in  which  case  it  would  be  necessary 
to  do  some  cutting  on  the  root  itself. 


TRIMMING  OF  THE  TEETH 


105 


The  bulk  of  this  enamel  can  always  be  removed  with  scalers 
or  enamel  cleavers,  and  it  is  very  rarely  that  any  other  instruments 
need  be  used. 

The  most  useful  instruments  for  this  purpose  are  an  enlarged 
special  No.  3  scaler  (Fig.  114)  and  also  the  Xo.  7  scaler,  which  is 
of  a  slightly  different  shape  and  much  thinner  (Fig.  115). 


Fif;.    117. — Shows  the  trimming  of  the  labial  and  aproxiinal  sides  of  the  rifiht 

fuspid  root. 


The.se  instruments  .should  have  large  handles  in  order  that 
the  operator  may  hold  them  with  a  firm  grip  and  have  perfect  control 
of  the  instrument  so  that  there  is  no  possibility  of  its  slii)ping,  or 
twisting  in  the  hand,  and  injuring  the  soft  tissues.  The  heavy 
handles  shown  in  the  illustration  will  be  found  mo.st  suitable  for 
u.se  with  these  trimmers  (Fig.  114). 

Trimming  the  RooIh  of  the  Upper  Anterior  Teeth. — In  working 
oil  the  upper  anterior  roots,  the  instrument  is  grasped  in  exactly 
the  same  manner  as  a  knife  is  held  in  shari)eiiiiig  a  pencil,  the  only 


106 


TYPICAL  SHAPES  OF   THE   TEETH 


difference  being  that  instead  of  resting  on  the  ball  of  the  thumb, 
the  end  of  the  thumb  is  placed  against  an  adjoining  tooth,  as  in 
Figs.  116  and  117,  and  the  force  exerted  to  strip  the  enamel  from 
the  root  by  a  slight  opening  and  closing  movement  of  the  hand. 
The  special  scaler  (Fig.  1 14)  is  of  such  shape  that  it  closely  follows 
the  contour  of  the  root.  It  is  passed  down  below  the  gum  line, 
crowding  the  gum  away  from  the  root  until  it  goes  beyond  the 
enamel  which  is  thus  stripped  off  until  the  root  is  perfectly  smooth. 


Fig.  118. — Shows  the  trimming  of  the  lingual  portions  of  the  left  cuspid  root, 
the  thumb  of  the  hand  holding  the  instrument,  resting  on  the  thumb  of  the  left 
hand. 


In  cases  where  the  stump  may  stand  by  itself,  and  there  is  no 
adjoining  tooth  on  which  to  secure  a  rest;  especially  if  the  gum 
be  somewhat  tender,  the  thumb  or  finger  of  the  other  hand  may  be 
placed  on  the  gum  with  the  end  of  the  thumb  of  the  hand  holding 
the  instrument  resting  against  it  (Figs.  118  and  119). 


TRIMMING  OF  THE  TEETH 


107 


As  we  go  farther  back  in  the  mouth,  especially  if  the  mouth  be 
small  and  the  cheeks  tense,  there  will  be  times  when  it  will  be 
impossible  to  hold  the  instrument  in  the  manner  described.  Then 
it  may  be  necessary  to  grasp  the  instrument  firmly  in  the  right 
hand,  and  exert  the  force  to  strip  the  enamel  with  the  thumb  or 
finger  of  the  left  hand.  The  illustrations  give  a  fair  idea  of  the 
manner  in  which  this  is  done  (Figs.  120  to  125). 


Fig.  lip, — Shows  trimmiriK  of  the  labial  side  of  loft  cuspid,  instrument  and  hands 
in  same  position  as  in  Fig.  118. 

Trimming  the  Hoots  of  the  Lower  Anterior  Teeth. — Trimming  the 
roots  of  the  lower  aJiterior  teeth  is  much  more  difficult  than  is  the 
trimming  of  the  roots  of  the  upper  and  the  dift'erent  portions  of 
the  roots  are  far  more  difficult  of  access.  It  is  impossible  to  hold 
the  instruments  in  the  maimer  in  which  they  are  held  in  trimming 
the  upper  roots.  The  same  instruments  are  used,  however,  the 
operator  standing  at  the  back,  and  to  the  left  of  the  patient,  the 


108 


TYPICAL  SHAPES  OF   THE   TEETH 


chair  being  in  its  lowest  position.  The  instrument  is  held  in  the 
right  hand,  and  as  nearly  on  a  line  with  the  long  axis  of  the  tooth 
as  possible. 

The  fingers  which  are  not  used  in  holding  the  trimmers  are 
braced  against  the  teeth  or  some  part  of  the  upper  jaw,  so  that 
there  will  be  no  possibility  of  the  operator  losing  control  of  the 
instrument  and  injuring  the  tissues.  The  principal  force  is  exerted 
with  the  thumb  and  finger  of  the  left  hand,  that  of  the  right  being 
used  only  to  steady  and  to  give  a  pull  to  the  instrument. 


Fig.  120. 


-Shows  trimming  of  right  second  bicuspid  from  buccal  side,  thumb  of 
right  hand  resting  on  thumb  of  left  hand. 


In  trimming  the  buccal  or  labial  surfaces  of  the  teeth  on  the 
right  side  of  the  mouth  and  around  to  the  median  line,  the  force 
used  in  stripping  the  enamel  is  exerted  by  the  first  finger  of  the 
left  hand,  the  thumb  being  braced  on  the  lingual  side  of  the  tooth 
or  jaw  and  in  such  a  manner  that  it  will  not  be  struck  by  the  point 
of  the  instrument.     The  instrument  is  passed  beneath  the  enamel 


TRIMMING  OF  THE  TEETH 


109 


and  pressed  tiglitly  against  the  root,  while  the  pull  is  being  exerted 
with  the  right  hand,  as  shown  in  Fig.  126.  Nearly  all  of  the  mesial 
and  distal  sides  of  the  teeth  may  also  be  reached  by  working  the 
instrument  in  the  same  wav. 


Via.   121. — Shows  nearly  same  position,  but  part  of  the  force  for  stripping  llic  inaniol 
exerted  by  thumb  of  left  hand. 


On  trimming  the  lingual  side  of  these  teeth,  the  force  is 
exerted  by  the  thumb  of  the  left  hand  and  the  fingers  are  braced 
on  the  buccal  c^r  labial  side  of  the  teeth  (Fig.  127).  In  trimming 
the  teeth  on  the  left  side  of  the  mouth,  these  methods  are  reversed, 
the  thumb  being  used  to  exert  the  force  when  working  on  the  buccal 


no 


TYPICAL  SHAPES  OF  THE  TEETH 


or  labial  sides  of  the  roots  and  the  fingers  when  working  on  the 
lingual  (Figs.  128  and  129). 

On  the  mesial  and  distal  sides,  the  force  is  applied  the  same  as 
for  the  buccal  and  lingual,  either  the  thumb  or  finger  being  used 
as  is  most  convenient. 

Where  the  operator  is  left-handed,  the  method  of  operating 
and  the  manner  of  holding  the  instrument  would  be  reversed. 


Fig.  122. — Shows  trimming  buccal  corners  of  upper  left  molar,  force  exerted  by  first 

finger  of  left  hand. 

The  enlarged  special  scaler  (Fig.  114)  is  used  on  the  labial  or 
lingual  sides  of  the  root  and  if  there  is  sufficient  room  between  it 
and  the  other  teeth  it  can  be  used  on  all  sides;  but  if  there  are  adjoin- 
ing teeth  so  close  as  to  prevent  this,  then  the  smaller  scaler  (Fig. 
115)  is  used  on  the  mesial  and  distal  sides. 

The  scaler  (Fig.  114)  is  the  most  universal,  and  can  be  used  in 
almost  every  position  where  there  is  sufficient  space  between  the 
teeth. 


TRIMMING  OF  THE  TEETH 


111 


At  times  the  enamel,  principally  of  the  cuspids  and  especially 
on  the  lingual  side,  is  so  heavy  and  so  very  firmly  attached  to  the 
dentin  that  it  is  impossible  to  start  it  with  these  instruments,  in  such 
cases,  the  Case  enamel  cleavers  may  be  used  to  start  with,  and 
afterward  the  finishing  is  done  with  Xo.  3  scales. 


Fig.   12.3. — Shows  trimming  of  lingual  corners  of  upper  left  molar,  force  exerted  by 

thunil)  of  left  hand. 

Tlie  C'a.se  enamel  cleavers  (Fig.  130)  have  a  strong  sharp  bit, 
and  are  very  useful  when  a  great  deal  of  force  is  necessary.  Their 
shape  is  sueli,  Iio\v('\(t,  that  they  do  not  leave  the  root  smooth;  the 
surface  from  wliicli  they  have  stripjx'd  the  enamel  is  left  in  grooves 
and  ridges,  s(;  that  it  is  necessary  to  follow  them  with  Xo.  3. 

\t  times,  even  these  instruments  will  not  break  the  enamel,  and 
it  becf)mes  neeessar\'  to  start  its  remoNal  with  small  carborundum 
points  or  diamc^nd  wheels,  finishing  with  the  Xo.  3  scaler. 


112  TYPICAL  SHAPES  OF  THE  TEETH 

FACING   ROOTS   FOR   VARIOUS   FORMS    OF   CROWNS. 

It  has  already  been  said  that  the  stump  should  be  left  standing 
for  a  considerable  distance  out  of  the  gum,  until  after  the  root  has 
been  trimmed  and  the  band  fitted. 

Richmond  Crowns. — In  the  case  of  a  Richmond  crown,  after  the 
root  has  been  trimmed,  the  band  fitted,  and  the  canal  enlarged. 


Fig.  124. 


-Shows  trimming  of  buccal  corners  of  upper  right  molar,  force  exerted  by 
thumb  of  left  hand. 


the  stump  is  cut  away  labially  to  from  one-thirty-second  to  one- 
sixteenth  of  an  inch  below  the  gum  margin,  so  that  when  the 
crown  is  completed  the  band  will  be  entirely  hidden.  Lingually, 
if  the  bite  will  permit,  it  may  be  left  standing  from  one-thirty- 
second  to  one-sixteenth  of  an  inch  out  of  the  gum,  so  as  to  give 


FACING  ROOTS  FOR   VARIOUS  FORMS  OF  CROWNS      113 

additional  support  and  strength  to  the  crown,  cutting  the  stump 
in  a  straight  hne  from  the  hngual  to  the  kibial  side  (Fig.  111). 
This  will  apply  to  single  crowns  or  those  used  as  abutments  for 
fixed  bridges. 


Fig.   125. — Sho.'...   lumuiing  of  lingual  corners  of  upper  right  molar,  force  exerted 
by  forefinger  of  left  hand. 


Porcelain  or  Downie  Crowns. — For  a  porcelain  crown  a  double  slope 
is  given  to  the  root.  The  root  is  cut  labially  to  the  same  depth 
below  the  gum  as  for  a  liichmond  crown,  but  lingually  it  should 
be  carried  just  to  the  gum  border,  leaving  it  high  in  the  center. 

The  reason  for  this  double  bevel,  instead  of  making  it  straight 

across  from  buccal  to  lingual,  is  that  it  is  necessary  to  festoon  the 

lower  edge  of  the  band  to  follow  the  gum  line,  and  also  to  allow  for 

a  greater  bulk  of  porcelain  in  order  to  give  increased  strength. 

8 


114 


TYPICAL  SHAPES  OF  THE  TEETH 


The  septum  of  the  process  comes  much  higher  up  on  the  root 
mesially  and  distally  than  it  does  at  the  buccal  and  hngual  sides 
of  the  teeth,  and  therefore  it  is  necessary  to  festoon  the  band 
accordingly  (Fig.  131). 


Fig.   126. — Shows  trimming  buccal  side  of  lower  teeth,  on  the  right  side  of  the  mouth, 
force  exerted  by  finger  of  left  hand. 


If  it  were  cut  straight  across,  in  order  to  place  a  perfectly  flat 
floor  on  the  band,  the  band  would  be  cut  entirely  away  mesially 
and  distally,  as  shown  in  Fig.  132.  As  previously  stated,  the  strength 
of  porcelain  is  only  in  proportion  to  its  bulk.  For  the  purpose  of 
illustration,  we  will  exaggerate  the  figure  somewhat,  so  as  to  make 
clear  the  reason  for  preparing  the  roots  in  the  manner  described. 


FACING  ROOTS  FOR  VARIOUS  FORMS  OF  CROWNS       115 

We  will  suppose  the  case  of  an  upper  bicuspid  crown  where  the 
bite  is  fairly  close.  It  will  be  noticed  that  by  giving?  a  direct  slope 
from  the  buccal  to  the  lingual  side,  as  would  be  done  if  it  were  a 
Richmond  crown,  that  when  the  facing  has  been  ground  in  place 
and   the   lingual   side   of  the   tooth   built   up  with   porcelain,   it 


Fig.   1:^7. — Shows  trimming  linguiil  side  of  lower  teeth  on  the  right  side  of  mouth, 
force  exerted  by  thumb  of  left  hand. 


would  render  it  very  weak  on  that  side,  and  would  be  quickly 
crushed,  as  there  is  so  very  little  porcelain  to  give  strength 
(Fig.  i:«). 

If  it  were  a  Richmond  crown  where  a  gold  back  was  to  be  used, 
then  of  r-ourse  it  would  not  make  the  slightest  difference,  as  a  small 


116 


TYPICAL  SHAPES  OF  THE  TEETH 


bulk  of  gold  at  this  point  would  give  far  greater  strength  than  would 
be  possible  if  it  were  made  of  porcelain. 

It  will  be  seen  that  if  the  tooth  is  cut  away  to  the  gum  line,  so 
as  to  give  it  a  double  slope  to  the  stump,  that  a  much  greater  bulk 
of  porcelain  could  be  used  with  a  corresponding  increase  in  the 
strength  of  the  crown  (Fig.  134). 


Fig.  128.- 


-Shows  trimming  of  buccal  side  of  lower  teeth  on  left  side  of  the  mouth, 
force  exerted  by  thumb  of  left  hand. 


The  facing  of  the  roots  may  be  done  with  a  square-edged  car- 
borundum wheel,  but  this  necessitates  an  unnecessary  mutilation 
of  the  gmn  tissue.  The  best  instruments  for  this  purpose  are  the 
Ottolengui  root  facers  (Fig.  135).  These  instruments  are  made  in 
different  sizes  to  correspond  with  the  different  teeth,  and  will 
do  the  work  perfectly  with  but  little  or  no  mutilation  of  the  soft 
tissue. 


FACING  ROOTS  FOR  VARIOUS  FORMS  OF  CROWNS       117 

As  these  instruments  come  from  the  dental  depots,  the  guide 
point  is  very  much  longer  than  it  should  be,  unless  the  root  is  to 
be  faced  perfectly  flat  and  at  right  angles  with  the  canal.  If,  in 
order  to  slope  the  face  of  the  root  in  either  direction,  the  instrument 


Fk;.  129. — Shows  trimming  lingual  side  of  lower  teeth  on  left  side  of  the  mouth, 
force  exerted  by  finger  of  left  hand. 


is  inclined  either  labially  or  lingually,  and  unless  the  canal  be  very 
much  enlarged  the  end  of  the  point  will  strike  the  opposite  wall  of 
the  canal  so  as  to  prevent  the  instrument  facing  tlie  tooth  on  an 
angle,  as  will  be  seen  in  the  illustration  (Fig,  136).  This  point  should 


118 


TYPICAL  SHAPES  OF  THE  TEETH 


be  ground  off  so  that  its  length  is  about  the  same  as  its  diameter, 
and  then  there  will  be  no  trouble  in  sloping  the  face  of  the  root  in 


Fig.   130. — Enamel  cleavers. 


the  desired  direction  (Figs.  137  and  138).  If  the  root  is  much 
decayed  and  enlarged  at  the  entrance  to  the  canal,  the  length  of 
the  pin  will  make  little  difference. 


Fig.  131 


Fro.  132. 


Fig.  133 


Fig.  134 


In  using  these  instruments,  it  will  frequently  be  found  that  a 
facer,  which  is  large  enough  to  cover  the  root  mesially  and  distally, 
will  not  reach  the  lingual  and  buccal  sides. 


I  ■ 

Fig.  135. — Root  facers. 


Fig.  136 


Fig.  137 


Fig.  138 


Fig.  139 


FACING  ROOTS  FOR  VARIOUS  FORMS  OF  CROWNS       119 

After  the  floor  has  been  united  to  the  })and  and  phiced  on  the 
root,  it  may  be  that  it  does  not  go  under  the  gum  so  as  to  be  hidden. 
On  removing  the  cap  and  examining  the  root,  it  will  be  seen  that 
the  facer  has  left  a  little  ridge  of  dentin  on  the  labial  side  which 
has  prevented  the  band  from  going  to  place  (Fig.  188).  Where 
such  is  the  case,  by  reaming  the  canal  a  little  labially  or  lingually 
as  shown  by  the  illustration  (Figs.  137  and  139),  and  enlarging  the 
entrance  to  the  canal  to  a  slight  depth,  it  will  allow  the  facer  to 
cover  the  root  at  both  of  these  places. 


CHAPTER  VII. 

IMPRESSIONS  AND  MODELS. 

An  impression  for  a  working  model  on  which  a  crown  or  bridge 
is  to  be  made  should  always  be  taken  in  plaster.  Modeling  com- 
position, wax  or  any  of  the  plastic  materials  which  are  used  for 
taking  impressions  should  not  be  used  for  a  working  model,  as  there 
is  no  plastic  impression  material  made  which  will  give  an  accurate 
impression  where  there  are  undercuts  or  dovetailed  spaces.  The 
material  will  draw  and  drag,  and  become  distorted  on  removing 
it  from  the  mouth,  with  the  result  that  the  model  made  from  such 
an  impression  will  be  imperfect. 

IMPRESSION    AND   MODEL   PLASTER. 

A  first  class  impression  plaster  should  be  fine  and  quick  setting, 
thus  rendering  the  impression  soft  and  easily  cut  away  from  the 
model  in  separating. 

A  good  model  plaster,  on  the  contrary,  is  coarse  and  slow  setting, 
and  becomes  very  hard. 

The  difference  between  a  good  impression  plaster  and  a  good 
model  plaster  can  be  instantly  determined  by  rubbing  it  between 
the  fingers.  The  impression  plaster  will  be  fine  and  smooth  like 
flour  between  the  fingers,  while  the  model  plaster  will  be  coarse 
and  the  grit  is  plainly  felt. 

If  so  situated  that  it  is  difficult  to  secure  the  different  grades  of 
plaster,  it  is  better  to  procure  the  hardest  model  plaster  that  it  is 
possible  to  get.  Then,  by  bolting  this  through  a  fine  cloth  a  good 
impression  plaster  will  be  secured,  in  the  finer  material  which  passes 
through  the  cloth,  and  at  the  same  time,  by  removing  this  fine 
plaster,  the  model  plaster  will  be  improved.  It  will  be  slower 
setting,  and  its  hardness  increased, 

WEINSTEIN'S    ARTIFICIAL   STONE. 

This  new  material  (a  calcium  barium  silicate)  is  eminently 
suitable    for   making    models    and    articulations    for    bridgework, 

(120) 


WEINSTEIN'S  ARTIFICIAL  STONE  121 

vulcanite  work,  and  other  purposes,  where  a  stronger  and  more 
durable  material  than  plaster  of  Paris  is  required.  INlodels  made 
from  it  are  remarkably  hard  and  durable  and  not  friable,  like 
plaster  of  Paris  or  any  of  the  Portland  cement  preparations. 

Another  most  valuable  property  of  the  artificial  stone  lies  in  the 
fact  that  it  possesses  practically  no  expansion  or  contraction. 
Upon  periodic  examination  of  a  number  of  specimens  under  test 
for  a  year,  no  measurable  change  was  found  after  the  initial  set 
had  taken  place.  It  contains  no  gritty  or  coarse  particles  and 
models  made  of  it  are  very  dense  and  smooth. 

The  following  instructions  for  manipulating  artificial  stone  are 
given  by  Mr.  Weinstein: 

Proportions  for  Mixing. — Accurate  proportioning  of  the  powxler 
and  the  water  that  it  is  mixed  with  is  imperative,  and  the  results 
far  more  than  repay  the  little  effort  that  it  takes  to  weigh  out  the 
powder  and  measure  the  water.  For  an  upper  or  lower  model,  the 
following  proportions  are  suitable:  To  1|  fluidounces  of  water 
add  78  to  SO  dwts.  (Troy)  of  the  artificial  stone  powder. 

The  mixing  is  done  in  a  rubber  bowl,  first  incorporating  approx- 
imately one-half  of  the  powder,  and  gradually  adding  the  balance, 
until  all  the  powder  is  thoroughly  incorporated.  If  the  propor- 
toins  taken  are  correct,  the  mass  will  be  as  stiff  as  a  very  thick  mix 
of  plaster. 

Preparation  of  Impressions. — The  impression,  if  plaster,  should  be 
\arnished  with  one  coat  of  shellac,  which  should  be  allowed  to  dry 
for  at  least  one-half  hour,  and  then  varnished  with  a  coat  of  san- 
darac,  which  should  be  allowed  to  dry  for  at  least  one  hour.  The 
impression  should  then  be  immersed  in  water  for  at  least  five 
minutes,  so  that  it  may  become  thoroughly  saturated.  It  is  then 
removed  and  the  excess  water  blown  off  with  compressed  air  or 
wiped  off  with  cotton,  leaving  the  surface  of  the  impression  moist, 
but  not  wet.  It  is  important  that  this  be  strictly  observed,  as  a 
dry  impression  will  absorb  moisture  from  the  artificial  stone,  while 
it  is  setting  and  produce  a  poor  model.  Modeling  compound,  or 
wax  imi>rcssions  rcf^uire  no  special  treatment. 

Filling  Impressions. — As  the  artificial  stone  is  mixed  quite  thick, 
it  cannot  be  poured  like  plaster,  but  must  be  brushed  or  packed 
carefully  into  all  deep  parts  before  filling  in  the  bulk  to  l)uil<l  up  a 
model.  To  facilitate  the  placing  of  the  material  into  deep  crevices 
or  depressions,  such  as  are  found  in  an  impression  of  a  case  with 
standing  teeth,  the  following  suggestion  will  prove  helpfiil :    i)repare 


122-  IMPRESSIONS  AND  MODELS 

mix  according  to  proportions  given;  take  off  about  one-half  tea- 
spoonful,  place  it  in  the  palm  of  the  hand,  or  on  a  cement  slab  and 
incorporate  with  it  some  additional  powder  until  it  becomes  as 
stiff  as  putty.  Prepare  from  this  small  mix  a  number  of  small 
cones,  lay  them  aside;  work  down  some  of  the  regular  mix  into  the 
deep  recesses,  using  a  small  brush  or  other  means,  then  place  a 
cone  into  each  depression  and  tamp  dow^n  with  a  small  stick  or  the 
eraser  end  of  a  lead  pencil.  This  will  serve  to  force  the  plastic  mix 
into  all  inaccessable  places.  The  balance  of  the  impression  may 
then  be  filled  in  practically  the  same  manner  as  in  manipulating 
a  thick  mix  of  ordinary  plaster.  As  this  material  sets  quite  slowly, 
ample  time  may  be  taken  to  fill  the  impression  carefully. 

Separating  Impression. — The  filled  impression  should  be  permitted 
to  set  at  least  four  hours  prior  to  separating;  however,  it  should  not 
be  allowed  to  stand  more  than  twelve  or  fifteen  hours  before  sepa- 
rating as  the  hardness  gradually  increases,  making  it  more  difficult 
to  do  the  required  trimming. 

The  model  will  become  as  hard  as  well-set  plaster  of  Paris  within 
six  or  seven  hours  after  pouring,  and  may  then  be  used  if  necessary. 
The  maximum  hardness  is  attained  within  thirty-six  to  forty-eight 
hours. 

IMPRESSION    AND   BITE. 

In  order  to  secure  perfect  results,  the  model  on  which  the  bridge 
is  to  be  constructed  must  be  as  nearly  perfect  as  it  is  possible  to 
make  it.  The  impression  must  be  clear  and  sharp,  so  that  the  caps 
and  bands,  which  have  been  in  position  in  the  mouth  when  the 
impression  was  taken,  will  fit  accurately  into  place. 

It  is  necessary  that  the  articulation  should  be  as  perfect  and 
accurate  as  is  the  model.  These  results  can  best  be  secured  by 
taking  what  is  known  as  a  "squash  bite,"  that  is,  taking  the 
impression  and  bite  simultaneously  in  plaster  and  by  so  doing 
far  better  results  will  be  obtained  than  it  is  possible  to  secure  in 
any  other  way. 

In  taking  the  impression  and  bite  in  this  manner,  the  plaster  is 
allowed  to  become  quite  hard  and  is  then  carefully  broken  away 
and  afterward  the  broken  parts  are  easily  assembled,  and  the 
model  secured  from  this  will  be  a  perfect  reproduction  of  the 
required  part  of  the  mouth. 

It  is  the  general  custom  to  take  the  impression  for  this  work  in 
the  ordinary  manner,  using  a  tray  for  the  purpose.     A  separate 


COLORING  AND  FLAVORING  IMPRESSION  PLASTERS    123 

bite  is  afterward  taken  in  wax  or  modeling  composition  and  the 
model  prepared  from  this.  It  is  not  possible  to  secure  anything 
like  the  accuracy,  in  taking  the  impression  and  bite  in  this  manner, 
as  it  is  by  taking  the  squash  bite  in  plaster. 

The  model  is  first  cast,  and  after  it  has  become  hard  and  has 
been  separated  the  waxed  bite  is  pressed  into  place.  It  generally 
happens  that  this  bite  has  to  be  trimmed  more  or  less  in  different 
places  before  it  can  be  pressed  into  position.  The  wax  being  hard, 
considerable  pressure  is  necessary  and  it  is  liable  to  be  forced 
farther  down  on  the  model  in  one  place  than  in  another,  with  the 
result  that  the  articulation  is  not  exactly  as  it  should  be.  Then, 
after  the  bridge  is  completed,  it  is  necessary  to  do  more  or  less 
articulating  when  it  is  adjusted  in  the  mouth.  This  necessitates 
taking  the  piece  to  the  laboratory  for  refinishing. 

Where  a  plaster  impression  and  articulation  has  been  taken  in  the 
manner  described,  it  is  possible  to  construct  a  bridge  and  finish  it  so 
that  when  it  is  placed  in  the  mouth  the  occlusion  will  be  so  nearly 
perfect  it  will  rarely  be  necessary  to  do  any  grinding  at  all. 

COLORING    AND    FLAVORING   IMPRESSION   PLASTERS. 

It  is  an  excellent  idea  to  tint  the  impression  plaster  slightly,  as 
this  difference  in  color  from  the  model  will  very  materially  aid  in 
separating  the  impression  from  the  model.  Another  good  plan  is  to 
flavbr  the  plaster  slightly.  It  has  been  the  custom  of  the  waiter 
for  many  years  to  tint  the  impression  with  carmine,  and  also  to  use  a 
few  drops  of  cologne  in  the  water  in  which  the  plaster  is  mixed.  This 
cologne  not  only  imparts  an  agreeable  flavor  to  the  plaster,  but  in 
many  instances  it  will  entirely  overcome  the  nausea  to  which  some 
patients  are  subject  when  plaster  is  placed  in  the  mouth.  It  has 
been  iouud  that  in  many  instances,  where  it  has  been  impossible 
to  get  a  plain  plaster  impression  without  the  patient  l)ecoming 
nauseated,  that  these  few  drops  of  cologne  water  will  entirely 
prevent  it. 

The  method  of  j^reparing  the  carmine  and  cologne  solution  is  as 
follows:  A  half  ounce  bottle  is  filled  about  one-quarter  full  with 
carmine,  and  the  bottle  then  filled  up  with  strong  ammonia,  this 
being  the  only  agent  available  that  will  thoroughly  dissolve  it. 
This  solution  is  well  shaken  until  the  carmine  is  all  dissolved.  The 
bottle  is  then  left  unstoi)pered  for  a  day  or  two,  until  the  fumes  of 
arnrnoiiia  have  jiassed  ofl'. 


124  IMPRESSIONS  AND  MODELS 

About  one-fifth  to  one-quarter  of  this  carmine  solution  is  put  in 
a  six  ounce  bottle  and  the  bottle  filled  with  cologne  and  this  gives 
us  the  coloring  and  flavoring  solution.  A  few  drops  of  the  solution 
is  added  to  the  water  in  which  the  plaster  is  to  be  mixed,  thus 
giving  it  the  color  and  flavor  desired.  The  cologne  used  should  be 
an  alkaline  solution,  as  should  it  be  acid  it  would  precipitate  the 
carmine. 

The  setting  of  the  plaster  may  be  hastened  in  many  ways,  and 
it  is  generally  desirable  that  this  be  done  in  taking  impressions. 
It  may  be  accomplished  by  mixing  the  plaster  with  warm  water 
or  bv  adding  to  the  water  a  little  common  salt,  or  potassium  sul- 
phate. Much  stirring  also  will  have  the  same  result.  The  pro- 
portions of  water  and  plaster  used  will  also  accelerate  or  retard 
the  setting.  The  writer  prefers  the  potassium  sulphate  for  this 
purpose,  as  very  little  will  accomplish  the  purpose,  and  it  does  not 
impart  a  disagreeable  taste  to  the  mixture  as  is  the  case  where  the 
salt  is  used. 

The  amount  used  depends  on  the  size  of  the  impression  which 
is  to  be  taken.  If  this  be  small,  we  can  use  proportionately  more 
than  we  could  for  a  large  impression,  as  a  longer  time  is  required 
to  spread  the  plaster  in  the  mouth  for  a  large  impression  than  it 
does  for  a  small  one.  In  the  case  of  a  full  impression,  very  little 
should  be- used,  and  at  times  none  at  ah.  The  amount  used,  how- 
ever, will  depend  upon  the  particular  batch  of  plaster  with  which 
we  are  working,  as  there  is  hardly  any  two  lots  of  plaster  which  will 
work  exactly  alike,  some  setting  much  more  quickly  than  do  others. 
Iia  getting  a  new  supply  of  plaster,  it  is  always  best  to  make  one  or 
two  mixes,  before  using  it  in  the  mouth,  in  order  to  become  familiar 
with  its  properties. 

To  get  the  best  results  for  impressions,  the  plaster  should  also 
be  thoroughly  mixed.  The  method  of  mixing  is  as  follows:  First 
place  a  little  of  the  potassium  sulphate  in  the  bowl,  adding  a  few 
drops  of  the  carmine  and  cologne  solution,  and  then  as  much  water 
as  is  needed  for  the  impression  under  consideration.  The  plaster 
should  never  be  thrown  in  the  bowl  carelessly  and  in  large  quantities, 
but  should  be  sifted  into  the  water  carefully  and  in  small  quantities, 
taking  it  on  the  spatula  and  sifting  it  round  the  edges  of  the  bowl. 
The  plaster  will  work  toward  and  settle  in  the  center  so  that  there 
will  be  no  air  confined  in  a  mass  of  dry  plaster. 

The  plaster  should  be  added  slowly  until  it  comes  just  about  to 
the  surface  of  the  water,  but  not  enough  is  used  to  take  up  all  the 
moisture.    This  is  then  carried  to  the  chair  without  stirring.    By 


TAKING  IMPRESSION   WITH  ABUTMENTS  IN  PLACE    125 

refraining  from  stirring  the  mix,  the  plaster  does  not  begin  to  set 
and  it  will  give  some  little  time  in  order  to  examine  the  mouth  and 
see  that  everything  is  all  right,  the  caps  in  position,  etc.  After  it 
has  been  ascertained  that  everything  is  as  it  should  be,  begin  mixing 
the  plaster,  stirring  it  with  the  flat  of  the  spatula  and  cutting  through 
the  mass  with  the  spatula  held  edgewise  to  work  out  the  air  bubbles. 
The  stirring  should  be  kept  up  until  the  plaster  is  just  stiff  enough 
so  that  it  will  not  drop  from  the  blade  of  the  spatula  when  it  is 
inverted.    It  is  then  ready  for  use  in  the  mouth. 

TAKING    THE   IMPRESSION   WITH    ABUTMENTS   IN   PLACE. 

First  cover  well  with  the  plaster  the  bands  or  caps  on  the  abut- 
ments, and  then  fill  in  the  spaces  between  the  abutments,  and  also 
taking  in  several  of  the  adjoining  teeth.  The  occlusal  surfaces  of 
the  occluding  teeth  are  also  covered  with  the  plaster. 

The  patient  is  then  instructed  to  close  the  mouth  tightly  and 
the  teeth  which  have  not  been  included  in  the  impression  are  care- 
fully examined  to  see  if  the  proper  closure  has  been  obtained. 

Securing  the  Proper  Closure. — At  times  it  is  very  difficult  to  get 
the  patient  to  close  the  mouth  properly  on  a  mass  of  plaster  or  wax. 
There  are  many  different  ways  of  inducing  the  patient  to  give  the 
proper  bite,  such  as  having  the  patient  swallow,  throwing  the  head 
far  back  while  closing  the  mouth,  and  at  times  even  using  force  to 
throw  the  chin  back  where  it  belongs. 

The  writer  has  frequently  found  that  where  every  other  method 
would  fail,  a  proper  occlusion  could  be  secured  if  the  patient  would 
turn  the  tip  of  the  tongue  as  far  back  on  the  soft  palate  as  possible 
and  hold  it  there  while  bringing  the  jaws  together.  It  will  be 
found  that  it  is  impossible  for  a  patient  to  give  a  wrong  closure  if 
the  tongue  is  held  in  this  position  until  the  jaws  are  closed,  as  the 
chin  cannot  be  thrust  forward  or  from  side  to  side  without  moving 
the  tongue. 

The  impression  should  be  left  in  the  mouth  until  the  plaster  has 
become  thoroughly  hard  and  brittle.  This  is  ascertained  by  testing 
from  time  to  time  the  plaster  remaining  in  the  bowl.  As  soon 
as  it  breaks  with  a  clean,  sharp  fracture,  and  when  a  small  particle 
rubbed  between  the  thumb  and  finger  cannot  be  crushed,  the 
impression  will  be  sufficiently  hard  to  be  removed  from  the  mouth, 
but  as  long  as  the  plaster  can  be  crushed  between  the  thumb  and 
finger  and  moisture  squeezed  from  it,  it  should  not  be  removed. 


126  IMPRESSIONS  AND  MODELS 

When  it  has  thoroughly  hardened,  the  patient  is  instructed  to 

open  the  mouth,  and  the  impression  is  carefully  removed,  every 

broken  particle  being  saved.     It  is  very  rarely  that  an  impression 

taken  in  this  manner  will  come  away  whole,  but  will  be  more  or 

less  broken  up,  sometimes  in  many  pieces.    It  is  well  to  have  a  little 

tray  with  the  bottom  covered  with  a  piece  of  blotting  paper,  on 

which  to  lay  the  impression.    The  broken  parts,  as  they  come  from 

the  mouth,  should  be  so  placed  on  the  tray  that  it  can  be  remembered 

where  they  belong.    This  will  render  much  easier  the  task  of  putting 

together  the  broken  impression. 

The  caps  and  bands  are  then  removed  from  the  abutments.    If 

any  of  the  abutments  are  in  the  anterior  part  of  the  mouth  where 

bands  are  supposed  to  be  hidden,  the  stumps  should  be  protected. 

This  can  generally  be  done  by  simply  taking  a  piece  of 

base  plate  gutta-percha  and  rolling  it  something  in  the 

shape  shown  in  Fig.  140.     The  root  is  then  thoroughly 

dried,  the  gutta-percha  slightly  heated  and  the  small  end 

^^„   introduced  into  the  canal.    The  bulbous  portion  is  then 
Fig.  140  ,        ^ 

pressed  over  the  face  of  the  root  carrying  it  well  over  the 
edge  and  forcing  the  soft  tissues  away.  This  will  prevent  the  gum 
from  growing  over  the  face  of  the  root,  and  will  render  the 
subsequent  placing  of  the  band  or  cap  much  easier  than  it  would 
otherwise  be. 

At  times  a  large-headed  tack  may  be  used  for  this  purpose. 
The  point  of  the  tack  can  be  shortened,  so  as  to  allow  the  head  to 
come  flush  with  the  gum  line.  The  shank  is  covered  with  base 
plate  gutta-percha,  and  it  is  then  warmed  and  forced  into  the 
root  and  the  surplus  gutta-percha  carried  over  the  head  of  the 
tack,  so  that  the  metal  will  be  covered  (Fig.  141). 

Treatment  of  Impression, — After  the  impression  has  been  removed 
from  the  mouth,  it  should  be  left  on  the  blotting  paper  for  from 
fifteen  to  twenty  minutes,  so  as  to  allow  the  excess  moist- 
ure to  be  absorbed,  but  not  long  enough  to  dry  the  plaster, 
as  the  impression  can  be  put  together  more  easily  and 
quickly,  and  also  more  accurately,  if  the  impression  is  a 
little  moist.    The  parts  are  then  carefully  assembled  and  fig.  141 
fastened  together  with  a  strong  wax.    The  wax  for  this 
purpose  should  be  sticky,  tough  and  sufficiently  hard  that  it  will 
not  bend  in  the  handling. 

The  writer  has  found  that  the  following  formula  will  make  the 
best  wax  for  this  purpose: 


TAKING  IMPRESSION   WITH  ABUTMENTS  IN  PLACE    127 

Pure  white  beeswax 16  ounces. 

Pure  white  resin  (powdered) 3  ounces. 

Gum  Damar  (powdered) 3  ounces. 

It  should  be  melted  in  the  order  given,  and  well  stirred  until 
the  powdered  resin  and  gum  damar  are  thoroughly  incorporated 
with  the  wax.  It  can  be  poured  in  cups  or  moulds,  or  rolled  into 
sticks  of  any  desirable  size  or  length. 

The  ordinary  dark  beeswax  and  dark  resin,  may  be  used  in  making 
the  wax,  but  it  does  not  make  a  hard  wax  that  is  as  clean  and  nice 
to  work  as  does  the  white.  We  must  be  certain,  however,  that  the 
beeswax  is  perfectly  pure.  If  there  should  be  the  slightest  trace  of 
paraffin  in  it,  the  wax  made  from  it  will  be  worthless. 

After  the  impression  has  been  put  together,  the  caps  and  bands 
are  put  back  in  it  in  their  original  positions,  care  being  taken  to 
see  that  they  fit  exactly  into  place.  They  are  then  waxed  firmly 
in  the  impression  with  sticky  wax.  In  the  case  of  an  anterior  abut- 
ment where  we  have  a  cap  and  tube,  the  cap  is  held  in  position  firmly 
with  the  instrument,  and  the  edges  of  the  band  are  waxed  tightly 
labially  and  lingually  (Fig.  142,  points  a  and  b)  before  waxing  it  on 
the  sides,  thus  holding  the  caps  immovable  while  the  sides  are  being 
waxed.  If  we  attach  it  in  one  place  only  at  first,  say  on  the  lingual 
side  of  the  cap,  the  contraction  of  the  wax  on  cooling  is  liable  to 
draw  the  cap  away  from  the  impression  labially,  thus  giving  to  it  a 
false  position,  so  that,  after  the  model  is  made  and  the  bridge  com- 
pleted, it  will  be  found  that  it  will  not  go  in  the  mouth  as  it  should. 

The  edges  of  the  caps  standing  out  of  the  impression  are  waxed 
heavily  on  the  outside  with  hard,  sticky  wax  (Fig,  143).  This  will 
not  only  hold  the  band  in  place,  but  will  also  help  to  hold  the 
impression  together.  The  inner  side  of  the  cap  is  covered  with  a 
very  thin  film  of  pink  paraffin  wax.     In  the  case  of  a  cap  for  a 


p  .n-  cz.  -n 


I-'k;.   142  V\(i.   143  Fiu.   144  Fig.   145 

shell  crown,  or  where  the  band  is  larger  at  the  occlusal  end  (Fig. 
144),  enough  wax  should  be  put  on  the  inside  of  the  band  to 
obliterate  aii>-  undercuts  or  do\'etai)ed  spaces  (Fig.  145).  If  there 
arc  i)ins  or  tubes  in  the  caps  they  should  also  be  covered  lightly 
witli  the  paraffin  and  wax. 


128  IMPRESSIONS  AND  MODELS 

The  gingival  edge  of  the  band  should  be  scraped  clear  of  wax, 
so  that  it  will  set  down  tightly  to  the  model.  The  obiect  in  having 
the  outer  edges  of  the  band  covered  thickly  with  wax  we  will  now 
explain. 

If  we  put  but  a  thin  film  of  wax  around  the  outer  edge,  as  we  do 
on  the  inside  of  the  band,  it  will  be  noticed  that  after  the  model 
has  been  made  and  the  band  removed,  that  the^e  is  a  fine  groove 
in  which  the  gingival  end  of  the  band  rests  (Fig.  146).  The  result 
will  be  that  after  taking  off  and  putting  on  the  cap  a  few  times, 
some  of  the  plaster  may  be  scraped  from  around  the  sides  of  the 
stump  which,  working  into  the  groove,  will  fill  it  partially,  with 


Fig.   146  Fig.   147  Fig.  148 

the  result  that  by  the  time  the  crown  is  completed,  the  band  may 
not  go  nearly  as  far  beneath  the  gum  as  it  was  originally  intended 
that  it  should  (Fig.  147);  whereas,  if  it  is  waxed  heavily  on  the  out- 
side, when  the  band  has  been  removed,  the  wax  is  stripped  away, 
leaving  a  wide  groove  on  the  model  around  the  stump,  so  that  if 
any  plaster  is  scraped  from  the  model  and  gets  into  the  groove,  it 
is  quickly  noticed  and  easily  removed  (Fig.  148). 

Separating  Medium. — Different  materials  are  used  for  this  purpose 
such  as  soap,  oil,  shellac,  or  sandarac  varnish,  or  shellac  and  san- 
darac  varnish  combined.  Oil  is  a  very  good  separating  medium 
but  the  surface  of  a  model  cast  in  an  oiled  impression  is  never  as 
hard  as  it  should  be,  and  it  is  also  more  liable  to  be  porous.  The 
same  may  be  said  of  soap,  as  a  separating  medium.  It  makes 
separating  the  impression  from  the  model  very  easy,  and  will  give 
a  clear-cut,  sharp-outlined  model,  but  as  in  the  case  of  the  oiled 
impression,  the  surface  of  the  model  will  not  be  ver^^  hard.  If  soap 
is  used,  after  using,  the  impression  should  be  thoroughly  washed 
with  clear  water,  otherwise  there  will  be  bubbles  and  a  porous 
surface  which  wi]l  render  the  model  unfit  for  use. 

Shellac  is  used  by  many  to  first  color  the  impression,  which  is 
then  given  a  coating  of  sandarac  varnish.  The  use  of  both  of  these 
varnishes  is  unnecessary,  as,  if  the  sandarac  varnish  is  slightly 
colored,  it  will  accomplish  the  object.  The  varnish  can  be  colored 
with  various  dyes,  but  a  very  simple  way  is  to  scrape  a  little  of  the 


TAKING  IMPRESSIONS  IN  SECTIONS  129 

crayon  of  an  indelible  pencil  into  the  varnish,  this  on  dissolving 
will  impart  to  it  a  purple  color.       <^ 

The  impression,  which  is  varnished  until  it  has  a  glazed  surface, 
will  give  a  model  with  a  much  smoother  and  harder  surface  than 
it  is  possible  to  secure  by  using  soap  or  oil.  However,  the  varnish 
should  not  be  so  thick  as  to  obliterate  the  fine  lines  which  we  wish 
to  preserve  in  the  model. 

The  impression  should  be  moist  in  order  to  take  the  varnish  and 
leave  a  glazed  surface.  If  it  is  placed  on  a  blotting  pad  and  left 
for  fifteen  or  twenty  minutes  after  the  impression  has  been  removed 
from  the  mouth,  it  is  generally  in  the  right  condition  to  take  the 
varnish  best.  If  the  model  is  too  dry,  the  varnish  Avill  soak  in  and 
not  give  a  glossy  surface.  If  the  impression  stands  for  some  hours 
after  taking  before  assembling  and  varnishing,  it  will  have  become 
too  dry,  and  should  be  dipped  in  water  and  then  placed  on  a  blotter 
for  a  few  minutes,  before  varnishing.  If  the  model  is  too  wet  the 
varnish  will  not  stick,  but  will  roll  up  and  scale  off. 

As  soon  as  the  varnish  has  hardened,  which  will  be  in  four  or  five 
minutes,  the  impression  can  be  dusted  with  talcum  powder,  w^hich 
is  afterward  blown  out  with  a  chip  blower.  This  will  render  the 
separation  of  the  impression  and  model  very  much  easier. 

TAKING   IMPRESSIONS   IN   SECTIONS. 

At  times  it  is  desirable  to  secure  an  impression  where  the  teeth 
are  very  much  loosened,  and  where  it  w^ould  be  impossible  to  obtain 
an  impression  in  an  ordinary  tray,  with  any  material,  without  risk 
of  removing  the  teeth  with  the  impression,  and  also  causing  the 
patient  considerable  pain. 

There  are  times  when  some  of  the  lower  incisors  may  be  so  loose 
that  it  would  be  possible  to  remove  them  easily  with  the  thumb 
and  finger,  yet  it  is  desirable  to  retain  them  in  position  for  a  time, 
with  some  kind  of  a  splint.  By  taking  the  impression  for  a  case  of 
this  kind  in  sections,  it  can  be  done  without  the  pain  to  the  patient, 
nor  the  slightest  danger  of  removing  the  teeth. 

The  plaster  is  prepared  and  mixed  the  same  as  described  for 
taking  an  impression  and  bite  simultaneously.  The  teeth  are 
pressed  into  their  proper  position  and  held  so  with  one  of  the 
fingers  of  the  left  hand  (Fig.  149).  With  the  aid  of  a  spatula 
the  plaster  is  placed  on  the  lingual  side  of  the  teeth  and  smoothed 
off,  letting  it  extend  a  little  above  the  iiuisal  edge. 
9 


130 


IMPRESSIONS  AND  MODELS 


After  the  plaster  has  hardened,  the  finger  is  removed  from  the 
labial  side,  the  plaster  holding  the  teeth  firmly  in  place.  The 
plaster  is  then  trimmed  flush  with  the  incisal  edges,  beveled  on  the 
lingual  side  and  then  slight  grooves  are  made  in  one  or  two  places 
to  serve  as  guides  in  putting  the  sections  together  (Fig.  150).  This 
is  now  covered  with  a  separating  medium  and  for  this  purpose  a 
soap  solution  is  most  convenient. 


Fig.   149 


A  fresh  mix  of  plaster  is  then  made,  and  the  labial  side  of  the 
teeth  is  covered  heavilv,  the  plaster  being  carried  over  the  incisal 
edges,  and  over  the  beveled  portion  of  the  plaster  impression  on 
the  lingual  side  (Fig.  151).  It  is  then  left  until  it  has  become  quite 
hard.  The  labial  side  of  the  impression  is  then  pried  away,  forcing 
it  outward  and  upward,  after  which  the  lingual  side  is  carefully 
removed. 

These  two  halves  are  then  put  together  and  waxed,  and  we  have 


TAKING  IMPRESSIONS  IN  SECTIONS 


131 


as  perfect  an  impression  as  it  is  possible  to  secure  (Fig.  152),  giving 
the  interspaces  between  the  teeth,  which  cannot  be  gotten  by  any  of 
the  ordinary  methods  of  impression  taking.  When  the  model  has 
been  made  from  this  impression,  it  gives  an  exact  reproduction  of 
the  teeth  in  their  normal  position,  from  which  a  splint  or  retaining 
bands  can  be  made. 


Fig.   150 


Fig.  151 


Fig.  152 


This  method  of  impression  taking  may  also  be  employed  to 
advantage  in  any  case  where  there  are  dovetail  spaces  or  deep 
undercuts.  It  is  also  valuable  in  securing  accurate  models  for 
orthodontic  or  other  purposes,  or  in  the  reproduction  of  models. 
When  it  is  desirable  to  get  a  very  accurate  impression  of  a  lower 
jaw,  where  the  teeth  are  inclined  very  much  lingually,  or  where  there 
are  do\'etail  interspaces  from  which  teeth  have  been  lost,  by  this 
method  impressions  of  the  greatest  accuracy  are  easily  obtained. 


Fig.  153 


In  securing  a  full  impression,  the  lingual  sides  of  the  teeth  are 
first  covered,  the  plaster  being  carried  well  down  over  the  gum, 
and  then  smoothed  so  that  the  sides  will  slope  away  from  the  sides 
of  the  teeth  the  same  as  a  core  on  an  undercut  model  in  getting  a 
mould  for  casting  a  die  (Fig.  153,  a  and  h).  The  upper  side  is 
trimmed,  preferably,  about  one-thirty-second  of  an  inch  below  the 
occlusal  surfaces  of  the  teeth.    The  plaster  is  then  given  a  coating 


132 


IMPRESSIONS  AND  MODELS 


of  the  soap  solution,  and  an  impression  taken  over  this,  using  an 
ordinary  tray,  carrying  it  well  down  over  the  plaster  which  has 
been  placed  on  the  lingual  sides  of  the  teeth  (Fig.  154). 


Fig.  154 

After  the  impression  has  hardened,  the  tray  is  removed  together 
with  the  impression,  leaving  the  plaster  cores  first  placed  on  the 
lingual  sides  of  the  teeth,  still  in  the  mouth  (Fig.  153,  a  and  b). 
These  pieces  are  then  pried  away  and  placed  back  in  the  impression 
in  the  tray  (Fig.  155). 


Fig.  155 


A  full  and  perfect  impression  of  the  mouth  has  thus  been  secured 
from  which  a  much  more  accurate  model  can  be  made  than  it  is 
possible  to  obtain  from  an  impression  taken  in  the  ordinary  manner. 


Fig.  156 


Fig.  157 


This  method  will  also  be  found  very  useful  where  an  exact  reproduc- 
tion of  a  plaster  model  is  desired. 


ARTICULATORS  133 

An  impression  of  dovetailed  interspaces,  from  which  teeth  have 
been  lost  (Fig.  150),  can  easily  be  obtained  by  putting  plaster  first 
on  the  lingual  side  of  the  teeth,  and  letting  it  come  to  about  half 
way  through  the  space  to  the  buccal  side.  This  is  smoothed  off, 
covered  with  a  separating  medium,  and  filled  in  from  the  buccal 
side  (Fig.  157),  and  an  impression  taken  over  that  in  a  tray  in 
the  manner  already  shown  in  Fig.  154. 

ARTICULATORS. 

In  crown  and  bridge-work,  the  question  of  occlusion  is  of  most 
vital  importance,  as  the  stability  and  life  of  the  work  depends  to 
a  very  great  extent  upon  its  proper  occlusion  with  the  opposing 
teeth. 

In  all  extensive  cases  of  bridge-work,  it  is  absolutely  essential 
that  only  first-class  anatomical  articulators,  capable  of  reproducing* 
the  natural,  lateral  or  triturating  movements  of  the  mandible,  so 
necessary  for  perfect  mastication,  should  be  used.  For  single 
crowns,  and  at  times  for  small  bridges,  it  is  permissible  to  use  some 
other  type. 

Nearly  all  of  the  small,  so-called  crown  articulators  on  the  market 
are  absolutely  worthless  so  far  as  securing  good  results  are  con- 
cerned. \yith  these  articulators,  the  only  movement  possible  is 
simply  the  up  and  down,  or  opening  and  closing  movement  of  the 
mandible.  Of  late,  a  few  small  articulators  have  been  placed  on 
the  market  which  are  capable  of  imitating  the  various  movements  of 
the  lower  jaw. 

A  plaster  articulator,  if  it  is  properly  made,  will  give  excellent 
results  for  single  crowns  and  also  for  small  bridges,  and  the  manner 
of  making  such  articulations  will  be  described  further  on. 

In  making  an  entire  denture,  the  matter  of  occlusion  is  of  especial 
importance,  and  the  difficulty  of  securing  an  accurate  occlusion 
is  far  greater  than  where  only  a  portion  of  the  teeth  are  to  be 
restored.  If  a  full  bridge  is  to  be  made  for  the  upper  jaw,  and  the 
majority  of  the  teeth  in  the  lower  jaw  are  in  place,  the  attachments 
for  the  molars  can  be  made  and  if  properly  articulated  will  then 
serve  as  a  guide  in  getting  the  bite,  or  the  occlusal  surfaces  of 
these  teeth  may  be  built  up  with  cement  so  as  to  interlock  with 
the  lower  teeth,  and  open  the  bite  to  the  proper  distance. 

In  the  majority  of  these  cases,  the  impression  and  bite  should 
be  taken  in  plaster,  the  same  as  in  smaller  cases,  and  the  face-bow 


134  IMPRESSIONS  AND  MODELS 

should  be  used  to  serve  as  a  guide  to  mount  the  models  properly 
on  the  articulator.  The  semicircular  plate,  to  which  the  stem  of 
the  face-bow  is  attached,  is  pressed  in  the  soft  plaster  as  soon  as 
the  patient  has  closed  the  mouth  and  the  upper  surface  of  the  disk 
partially  freed  from  the  plaster,  as  it  is  necessary  to  remove  it  to 
permit  of  the  plaster  impression  being  nearly  all  cut  away  before 
the  model  is  mounted  on  the  articulator. 

The  face-bow  is  used  in  exactly  the  same  manner  as  in  taking  a 
wax  bite  for. a  plate.  The  index  rods  are  adjusted  to  the  external  ends 
of  the  condyles  and  the  stem  of  the  plate,  which  is  imbedded  in 
the  plaster,  is  fastened  in  the  clamping  device  and  the  whole 
retained  in  place  until  the  plaster  has  thoroughly  hardened,  when 
the  impression  with  the  bow  attached  is  removed  from  the  mouth. 

It  will  be  remembered  that  after  imbedding  the  disk  in  the  impres- 
sion, the  plaster  has  been  scraped  partially  away  from  the  upper 
surface  for  the  purpose  of  weakening  it  so  that  the  disk  can  easily 
be  removed.  This  is  done  by  holding  the  impression  m  one  hand 
and  grasping  the  stem  in  the  other  and  lifting  it  until  it  breaks 
away,  care  being  used  not  to  disarrange  the  adjustment  of  the  stem 
in  the  bow. 

The  caps  and  bands  are  now  removed  from  the  mouth  and  care- 
fully placed  in  the  impression  and  waxed  in  place,  in  the  manner 
already  described,  and  the  impression  varnished.  After  varnishing 
it  is  well  dusted  with  talcum  powder  and  the  surplus  powder  is 
blown  out  with  the  chip-blower  so  as  to  render  the  separating 
easier. 

The  lower  half  of  the  model  is  cast  first  and  the  surplus  plaster 
placed  on  a  slab.  The  model  is  then  placed  on  the  plaster  and 
leveled  very  carefully.  After  this  has  hardened,  the  upper  side  is 
cast  and  this  is  also  inverted  and  placed  on  the  surplus  plaster  on  the 
slab,  leveling  it  so  that  this  side  is  parallel  with  the  lower  half.  In 
casting  both  the  upper  and  the  lower,  care  must  be  used  not  to  get 
any  plaster  at  the  point  where  the  plate,  from  the  face-bow,  has 
been  broken  away. 

After  the  model  has  thoroughly  hardened,  the  bulk  of  the  impres- 
sion is  carefully  cut  away,  simply  leaving  a  few  points  of  contact 
to  hold  the  halves  in  position  and  also  preserving  the  surfaces  where 
the  semicircular  plate  has  been  attached.  The  plate  is  then  carefully 
fitted  in  its  proper  position  and  waxed  firmly  in  place.  The  bow 
is  attached  to  the  articulator  and  the  models  are  fastened  and 
built  up  properly  with  plaster.     The  face-bow  is  now  removed 


ARTICULATORS 


135 


from  the  articulator  and  the  remainder  of  the  impression  is  cut 
away,  thus  releasing  the  halves  and  giving  a  perfectly  occluding 
working  model. 

In  making  a  full  denture,  it  is  more  necessary,  than  in  small 
cases,  that  the  articulator  which  is  used  should  be  one  which  will 
give  all  the  natural  movements  of  the  mandible.  The  Gritman 
or  Snow  articulator  is  recommended,  being  simple  and  easy  of 
manipulation  (Fig.  158). 

If  the  face-bow  has  not  been  used,  the  model  is  prepared  in  the 
same  way,  casting  the  lower  half  first  and  leveling  it  very  carefully 
on  the  surplus  plaster  on  the  slab,  sa  that  the  occlusal  plane  will 
be  as  nearly  correct  as  it  is  possible  to  make  it.  The  upper  half 
is  then  cast  in  the  same  manner  and  made  so  that  the  upper  and 
lower  surfaces  are  perfecth'  parallel. 


Fig.  158 


After  the  model  has  thoroughly  hardened,  the  impression  is  cut 
away,  leaving  only  three  or  four  points  of  contact  to  retain  the 
parts  in  their  normal  position.  In  such  cases,  the  anterior  part 
should  be  well  exposed,  and  also  the  buccal  sides  of  the  molars 
on  each  side  of  the  model,  so  that  the  position  of  the  median  line 
can  be  determined.  The  exposed  parts  will  serve  as  a  guide  in 
mounting  it  on  the  articulator,  after  which  the  remaining  parts  of 
the  impression  can  be  cut  away. 

Making  a  Plaster  Articulation. — It  is  always  best  to  follow  some 
fixed  rule  in  making  small  models  from  a  "squash"  plaster  impres- 
sion and  bite.  In  fact,  to  follow  some  fixed  rule  of  procedure  in 
all  of  our  operations  will  be  time-saving.  The  lower  half  of  the 
model  is  always  cast  first,  irrespectiv^e  of  which  jaw  the  bridge  is 
being  made  for.    The  object  of  this  is  as  follows: 


136 


IMPRESSIONS  AND  MODELS 


A  very  large  proportion  of  bridges  made  are  those  which  restore 
teeth  which  have  been  lost  from  either  side  of  the  mouth,  extending 
from  the  bicuspids  to  the  molars.  The  models  for  these  cases  will  often 
be  made  on  nearly  a  straight  line,  their  shape  giving  no  clue  as  to  which 
side  of  the  mouth  they  belong.  After  the  two  halves  have  been  cast, 
the  next  step,  after  removing  it  from  the  slab,  will  be  to  cut  away 
the  surplus  plaster,  and  do  a  portion  of  the  trimming  before  separat- 
ing. If  the  rule  of  casting  the  lower  half  of  the  model  first  has  been 
followed,  as  soon  as  the  distal  portion  of  the  model  has  been  trimmed 


Fig.  159 


sufficiently  to  show  upon  which  half  the  grooves  were  cut,  it  can  be 
told  at  a  glance  which  is  the  upper  and  which  is  the  lower  half. 
(Fig.  159).  This  enables  the  operator  to  tell  very  nearly  where  the 
abutments  are  located,  and  knowing  this,  the  impression  can  be  cut 
away  more  quickly  and  certainly  than  if  the  models  were  made  in 
a  haphazard  way.  In  the  latter  case,  the  operator  would  have  to 
work  much  more  slowly,  carefully  cutting  into  the  impression  until 
a  part  of  the  model  was  exposed,  before  determining  which  was  the 
upper  and  which  was  the  lower,  thus  losing  many  minutes  of  valu- 
able time. 

CASTING  OF  PLASTER  MODELS. 

The  models  should  always  be  well  made  and  neatly  prepared, 
and  should  also  be  of  a  size  corresponding  to  that  of  the  work 
which  is  to  be  done  upon  them. 


CASTING  OF  PLASTER  MODELS 


137 


A  piece  of  work  should  never  be  undertaken  on  an  irregular  and 
ungainly  mass  of  plaster,  called  a  model.  The  models  should  be 
carved  and  finished  neatly.  It  is  an  old  saying  that  a  good  workman 
can  do  good  work  with  poor  tools  and  instruments,  but  there  is  no 
question  but  that  he  could  do  much  better  work  if  he  had  better 
toojs  and  instruments  with  which  to  do  it  with,  and  so  can  a  man 
do  much  better  work  on  a  model  which  is  well 
and  neatly  prepared  than  it  is  possible  to  do 
on  one  which  is  poorly  made. 

As  previously  stated,  the  model  plaster 
should  set  very  hard  and  is  coarser  than  the 
impression  plaster.  The  difference  between 
the  two  can  be  readily  distinguished  by  simply 
rubbing  it  between  the  fingers,  the  impression 
plaster  being  fine  and  smooth  like  flour,  while 
the  model  plaster  will  feel  coarse  and  rough  in 
comparison.  In  mixing  the  plaster,  cold  water 
is  used  and  nothing  should  be  added  to  hasten  the  setting  as  this 
will  tend  to  make  a  softer  model.  It  should  be  stirred  very  lightly, 
as  much  stirring  has  a  tendency  to  hasten  the  setting  of  the  plaster, 
thus  making  it  softer.  The  water  is  first  put  in  the  bowl  and  then 
the  plaster  carefully  sifted  from  the  knife  or  spatula  around  the 
edges  of  the  bowl,  allowing  it  to  work  toward  the  center.     The 


Fig.  160 


Fig.  161 


plaster  is  slowly  added  until  all  the  moisture  is  taken  up  so  that  it 
will  be  a  fairly  stiff  mass.  The  plaster  should  never  be  so  soft  that 
it  can  be  poured  into  the  impressions.  It  is  well  to  remember  that 
the  stiffer  the  plaster  is  mixed,  the  harder  will  be  the  model.  It 
should  be  stirred  just  enough  to  thoroughly  incorporate  the  plaster 
and  follow  this  by  cutting  through  the  mass,  with  the  spatula  edge- 
wise, to  work  out  any  air  bubbles  which  may  be  there. 


138 


IMPRESSIONS  AND  MODELS 


The  impression  previously  coated  with  separating  solution  and 
dusted  with  talcum  powder,  is  dipped  in  water  and  the  water  lightly 
shaken  out,  leaving  very  little  in  the  deeper  parts.  A  small  portion 
of  the  plaster  is  then  placed  on  the  sides  of  the  impression  and 
worked  down  into  the  deeper  parts  by  jarring  it 
with  the  hand  (Fig.  160),  adding  a  little  at  a  time, 
and  working  it  down  gradually,  so  that  no  air 
bubbles  are  enclosed  in  the  mass.  This  is  con- 
tinued until  the  impression  is  filled.  The  excess 
of  plaster  is  then  placed  on  a  glass  slab  and  the 
impression  inverted  and  pressed  into  it.  The 
excess  plaster  should  extend  about  one  and  one- 
half  inches  back  of  the  impression  (Fig.  161). 
This  can  then  be  smoothed  off  and  grooves  cut 
into  it  to  the  depth  of  a  little  less  than  one-eighth 
of  an  inch,  say  about  three  thirty-seconds,  one 
groove  being  cut  at  right  angles  to  the  mass,  and 
the  other  parallel  with  the  sides  and  in  the  center 
of  the  extension  (Fig.  161). 

A  simpler  and  quicker  method  is  to  use  the 
little  articulating  plates  designed  by  the  writer, 
and  which  can  be  purchased  at  any  of  the  dental  depots  (Fig.  162). 
They  were  carefully  designed  and  much  study  was  given  to  the 
depth  of  the  grooves  which  they  would  make  in  the  plaster.  The 
grooves  are  made  so  that  with  the  lateral  movement,  the  model 


Fig.  162 


Fig.  163 


will  be  raised  and  lowered  to  about  the  same  degree  as  the  cusps 
would  give  to  the  same  movement  in  the  mouth.  If  the  grooves 
are  made  too  deep,  in  moving  the  model  in  any  direction,  the 
articulator  would  be  opened  too  wide,  and  if  they  are  too  shallow 
the  movement  would  not  be  sufficient. 
These  articulating   plates  are  used  as  follows:     The  excess  of 


CASTING  OF  PLASTER  MODELS 


139 


plaster  is  extended  backward  from  the  impression  about  one  and 
one-half  inches.  The  lower  side  of  the  plate  is  moistened  and 
covered  with  soft  plaster  and  is  then  pressed  into  the  surplus  extend- 
ing back  of  the  impression,  so  as  to  come  even  with  the  occlusal 
surfaces  of  the  teeth  (Fig.  163).  The  excess  of  plaster  is  trimmed 
away  from  the  impression  and  flush  with  the  edges  of  the  plate 
and  the  model  left  until  the  plate  will  come  away  by  simply  touching 
it  lightly  on  the  under  side  of  the  extending  handle.     This  will 


Fig.  164 


Fic.   165 


generally  be  in  from  five  to  eight  minutes  after  the  model  has 
been  cast.  It  is  not  well  to  undertake  to  remove  the  plate  forcil)Iy 
before  the  plaster  has  hardened,  as  if  this  is  done  the  plaster  will 
adhere  to  it  and  will  roughen  the  articulating  surface. 

After  the  plate  has  been  removed,  the  grooves  will  be  in  the  right 
position  and  of  i)roi)er  depth.  The  model  is  loosened  from  the  slab 
by  holding  the  slab  over  the  Bunsen  flame  for  an  instant.     The 


140  ~  IMPRESSIONS  AND  MODELS 

model  is  trimmed,  the  sides  smoothed  and  the  articulating  surface 
varnished  with  the  colored  sandarac. 

The  second  or  upper  half  is  now  cast  in  exactly  the  same  way, 
wetting  it  and  then  jarring  the  plaster  in,  a  little  at  a  time,  until 
the  impression  is  filled  and  the  plaster  carried  back  to  about  the 
same  depth  over  the  articulating  surface. 

The  excess  plaster  is  then  put  on  the  slab  as  before  and  the  piece 
inverted  and  pressed  into  it,  keeping  both  sides  parallel.  After 
it  has  become  sufiiciently  hard  to  remove  it  from  the  slab,  it  can 
be  trimmed  and  smoothed,  preparatory  to  separating. 

In  making  the  articulation,  the  model  should  be  made  to  articu- 
late so  that  the  movements  will  be  exactly  the  same  as  in  the  mouth. 
If  the  crown  or  bridge  is  on  the  side  of  the  mouth,  the  articulation 
should  be  carried  directly  back  from  the  molars  following  the  line 
of  the  arch  (Fig.  164).  If  it  is  in  the  anterior  part  of  the  mouth,  it 
should  be  directly  back  of  and  in  line  with  the  median  line  and  the 
center  of  the  palate  (Fig.  165). 

SEPARATING    THE   IMPRESSION   FROM   THE    MODEL. 

When  the  plaster  for  the  impression  has  been  tinted,  the  impres- 
sion and  model  are  easily  distinguished  by  the  difference  in  coloring. 
It  can  readily  be  seen,  from  having  run  the  lower  half  first,  on  which 
half  of  the  model  the  bridge  is  to  be  made,  and  knowing  that  the 
occlusal  surfaces  of  teeth  are  on  a  line  with  the  articulating  surfaces 
of  the  model,  it  is  possible  to  determine  very  nearly  where  the  abut- 
ments are  located.  The  impression  is  rapidly  cut  away  over  these 
abutments  until  they  are  exposed,  and  they  will  serve  as  a  guide  for 
removing  the  remainder  of  the  impression.  This  should  be  done  very 
carefully  and  after  it  has  been  removed,  the  separation  of  the  bal- 
ance can  very  easily  be  completed  by  working  them  slightly  from  side 
to  side  or  introducing  the  point  of  the  knife  between  the  forward 
end  of  the  articulating  surface  and  rotating  it  a  little.  The  model 
is  then  trimmed  and  carved  as  may  be  desired. 

Preparing  Working  Models. — In  making  a  bridge  for  the  back  of 
the  mouth,  where  the  abutments  are  to  be  shell  or  telescope  crowns, 
if, the  teeth  are  properly  prepared,  the  entire  work  of  making  the 
bands  and  completing  the  bridge  can  be  done  on  the  model.  There 
will  be  no  necessity  for  seeing  the  patient  after  we  have  taken 
the  impression  and  bite,  and  we  can  be  sure  that  the  bridge,  when 
completed,  will  go  in  place  as  it  should. 


SEPARATIXG   THE  IMPRESSION  FROM    THE  MODEL     141 

When  the  work  is  to  be  done  entirely  on  the  model,  the  teeth 
must  be  carefully  and  accurately  trimmed,  and  not  only  should  the 
abutments  be  parallel,  but  there  must  be  no  ledges  below  the  gum 
line  which  will  interfere  with  the  placing  of  the  bands  in  position. 

Extreme  accuracy  in  the  preparation  of  the  abutments,  so  that 
the  sides  will  be  only  slightly  larger  beneath  the  gum  line  and 
practically  free  from  ledges,  will  come  only  with  practice,  and  bv 
using  great  care  in  the  work.  The  knowledge  that  if  this  perfect 
preparation  is  accomplished,  all  of  the  work  can  be  performed  out 
of  the  mouth,  will  serve  as  an  incentive  for  the  operator  to  put 
forth  his  best  efforts. 

It  is  always  advisable  to  do  as  much  of  the  work  as  possible  on 
the  model  and  only  such  as  may  be  necessary  in  the  mouth,  as  the 
moral  effect  on  the  patient  is  something  to  be  desired.  It  does 
not  make  any  difference  how  skillful  the  operator  may  be,  his  best 
efforts  will,  at  times,  seem  clumsy  to  the  patient.  They  do  not 
always  realize  the  care  and  accuracy  which  is  absolutely  essential 
in  fitting  the  band.  The  constant  taking  off,  trimming  and  replac- 
ing the  bands  on  the  teeth  is  necessarily  painful,  and  may  often 
suggest  to  them  that  if  the  operator  was  as  skillful  as  they  had 
supposed,  he  should  be  able  to  do  the  work  more  quickly,  and  with 
less  pain.  On  the  other  hand,  if,  after  the  impression  has  been 
taken,  they  are  not  required  to  call  again  until  after  the  bridge  is 
completed,  it  will  seem  to  them  marvelous  that  such  beautiful  work 
could  be  produced  from  an  impression  that  appeared  to  them  to  be 
but  a  few  worthless  bits  of  broken  plaster,  and  they  will  immedi- 
ately be  inspired  with  a  much  higher  opinion  of  the  skill 
and  abilities  of  their  dentist. 

After  the  models  have  been  separated  and  carved,  they 
should  be  thoroughly  dried  with  a  gentle  heat.  If  they 
are  dried  rapidly,  the  plaster  will  become  baked,  with  the 
result  that  it  will  be  soft  and  chalky,  easily  crum})Ie(l 
between  the  fingers,  and  worthless  as  a  model.  In  cold 
weather,  by  placing  the  models  in  front  of  a  register  or 
over  a  radiator,  the  proper  amount  of  heat  to  dry  them 
slowly  and  render  the  models  hard  will  be  obtained.  '° 

After  the  models  are  thoroughly  dried  out,  they  should 
be  <-arcfully  trimmed.     This   is  best  done  with   a  fairly    'gogg  '~ 
bn^ad  hoe-shaped  excavator  (Fig.  KUi),  with  the  edges  of 
the  inner  sides  of  the  instrument  slightly  rounded  so  that  it  will 
not  scrape  the  sides  of  the  abutments.    The  plaster  is  carefully  cut 


142 


IMPRESSIONS  AND  MODELS 


away  to  about  one-sixteenth  of  an  inch  beneath  the  gum  Hue,  using 
great  care  to  cut  to  the  same  depth  all  around,  and  also,  not  to 
scrape  the  sides  of  the  stumps  so  as  to  change  their  size  and  shape, 
otherwise  bands  which  are  fitted  to  the  model  will  not  fit  the  teeth 
in  the  mouth  (Fig.  167). 

After  the  stumps  have  been  carefully  trimmed,  the  models  should 
be  thoroughly  saturated  with  dilute  sandarac  varnish.  This  can 
be  done  by  using  a  brush  and  painting  them  repeatedly  with  the 
solution,  giving  them  one  coating  after  another 
as  long  as  the  varnish  will  soak  into  the  plaster, 
or  until  it  begins  to  glaze.  If  the  models  are  not 
too  large,  they  may  be  placed  in  a  large  jar  of 
the  varnish  and  left  in  it  until  they  have  taken 
up  all  that  they  will.  The  varnish  should  be 
thin  so  that  it  will  soak  well  into  the  plaster. 
The  sandarac  varnish  as  procured  at  the  dental 
depots,  diluted  from  one-half  to  three-quarters  with  alcohol,  will 
be  of  about  the  right  consistency. 

The  models  are  now  again  dried  out  thoroughly  with  a  gentle 
heat,  and  it  will  be  found  that  the  surfaces  are  extremely  hard. 
By  using  care,  a  number  of  pieces  might  be  made  on  the  same 
model,  with  but  little  or  no  abrasion  of  the  stumps. 

There  are  other  ways  of  hardening  models.  A  favorite  one  is, 
after  they  have  been  carefully  prepared  and  thoroughly  dried, 
to  boil  them  in  sterine  or  paraffin.  This  makes  a  beautiful  model, 
but  one  not  as  good  to  work  on  as  those  which  have  been  treated 
with  sandarac  varnish.  The  varnish  makes  them  much  harder 
and  gives  them  a  better  wearing  surface. 


Fig.  167 


CHAPTER  VIII. 

BUILDING  UP  BROKEN-DOWN  ROOTS  WITH  AMALGAM 
PREPARATORY  TO  CROWNING. 

The  building  up  of  roots  with  amalgam,  preparatory  to  crowning, 
is  a  very  questionable  proceeding.  Every  dentist  knows,  or  should 
know,  that  gold  antl  mercury  have  a  great  affinity  for  each  other. 
It  is  this  known  affinity  of  the  metals  which  is  taken  advantage 
of  in  the  treatment  of  gold  by  the  amalgamation  process.  If  the 
mercury  could  be  entirely  removed  from  the  amalgam  of  course 
there  would  be  no  objection  to  its  use,  but  this  cannot  be  done  and 
if  it  could,  it  would  no  longer  be  an  amalgam. 

The  gold  crown,  coming  in  contact  with  the  amalgam,  is  attacked 
by  the  mercury  and  disintegrated.  Many  times,  even  where  gold 
bands  come  in  contact  with  old  amalgam  fillings  which  have  been 


Fig.  168  Fig.  169 

in  the  mouth  for  years,  the  effect  will  be  the  same.  The  writer 
has  seen  many  instances  of  this  kind,  where  a  tooth  having  amalgam 
filling  has  been  covered  with  a  gold  crown,  the  band  coming  in  con- 
tact with  the  filling,  with  the  result  that  within  a  year  or  two  the 
entire  side  of  the  cnnvn  has  been  disintegrated  and  broken  away. 
Of  course,  if  the  band  be  made  of  crown  metal,  or  of  platinum,  the 
eff'ec-t  would  not  be  so  marked,  but  the  platinum  caps,  in  connection 
with  the  bridge,  arc  undesirable  and  unsightly. 

Another  objection  to  tiiis  method,  ignoring  entirely  the  remark- 
able affinit>-  which  gold  and  mercury  have  for  each  other,  is  that 
from  a  practical  staiid|)oint,  in  the  majority  of  cases,  in  a  root  so 
built  \\]>  with  amalgam,  the  amalgam  stump  is  in  reality  an  element 
of  weakness  rather  than  of  strength. 

(143) 


144  BUILDING   UP  BROKEN-DOWN  ROOTS 

We  will  take,  for  example,  a  molar  which  is  broken  or  decayed 
well  below  the  gum  line.  The  general  practice,  in  building  up  these 
roots,  is  to  put  pins  in  the  canals  and  then  build  the  stump  above 
the  gum,  trimming  the  amalgam  flush  with  the  sides  of  the  stump 
(Fig.  168).  The  band  is  fitted  to  the  amalgam  stump,  the  crown 
made  and  the  bridge  connected  to  it  (Fig.  169). 

In  masticating,  the  lateral  strain  on  this  stump  is  very  great 
and  the  tendency  is  for  the  amalgam  to  pull  away  from  the  face  of 
the  root  labially  and  lingually,  allowing  moisture  to  work  in,  with 
the  result  that  the  tooth  or  stump  will  decay,  eventually  resulting 
in  its  entire  destruction.  We  say  that  there  is  a  tendency  for  this 
to  happen,  but  there  is  more  than  a  tendency  .  There  is  an  absolute 
certainty  that  this  will  occur  sooner  or  later.  There  is  also  a  lia- 
bility of  the  root  becoming  fractured  from  the  extra  strain  which 
is  thus  placed  upon  it. 

CROWNING   BROKEN-DOWN   ROOTS. 

When  a  tooth  is  broken  or  decayed  below  the  gum  line,  the  band 
should  always  be  carried  below  the  line  of  fracture  or  decay  in 
order  that  the  root  may  be  perfectly  protected. 

In  a  majority  of  cases  of  this  kind,  it  is  practically  impossible  to  fit 
the  band  in  the  mouth  or  indeed,  even  to  get  a  correct  measurement 
of  the  root.  Even  if  it  were  possible  to  do  so,  it  could  be  done  only 
at  the  expense  of  excruciating  pain  to  the  patient.  In  all  cases  of 
this  class,  the  band  should  be  made  and  fitted  to  a  carefully  prepared 
model. 

Taking  Impression  and  Preparing  Models  for  Broken-down  Teeth 
or  Roots. — We  will  consider  first  a  very  common  example  of  this 
class.  An  upper  first  or  second  bicuspid.  The  roots  of  these  teeth 
are  often  found  decayed  far  below  the  gum  line.  Sometimes,  on 
the  mesial  and  distal  sides,  below  the  process,  while  on  the  buccal 
and  lingual  sides  they  may  be  decayed  beneath  the  gum,  but  not 
to  the  same  depth  as  mesially  and  distally  (Fig.  170).  It  can  be 
readily  seen  that  a  root  in  this  condition,  cannot  be  treated  in  the 
same  manner  as  one  which  is  standing  out  of  the  gum,  and  the 
only  method  which  can  possibly  be  followed  with  accuracy  and  a 
minimum  amount  of  pain  to  the  patient  is  to  first  secure  an  accurate 
impression  of  the  face  of  the  root  and  then  prepare  a  model  on 
which  to  fit  the  band. 

Usually  the  gum  tissue  has. grown  over  the  stump.  This  must 
first  be  removed,  either  by  cutting  it  away  with  gum  scissors  or  a 


CROWNING  BROKEN-DOWN  ROOTS 


145 


lancet,  or  by  using  trichloracetic  acid  or  some  other  powerful 
escharotic.  After  this  has  been  done,  it  is  better,  in  order  to  still 
further  free  the  root-end  from  the  gum  tissue,  to  pack  it  tightly 
with  gutta-percha  or  cotton,  and  let  it  remain  for  a  day  or  two,  so 
that  when  the  work  is  commenced,  the  face  of  the  root  may  be  per- 
fectly free  from  all  intruding  tissue. 

It  is  rarely  that  there  is  much  trimming  to  be  done  on  such 
roots,  as  the  decay  has  generally  passed  beyond  the  line  of  enamel 
to  a  point  where  the  sides  of  the  root  are  nearly  parallel.  The 
little  trimming  may  be  necessary  should  be  carefully  done,  and 
with  very  sharp  instruments. 


Fig.  170 


Fig.  171 


Fig.  172 


Fig.   173 


In  such  a  case  it  is  plainly  impossible  to  get  an  accurate  impres- 
sion with  plaster.  A  material  must  be  used  which  will  force  the 
soft  tissues  away  from  around  its  margin'^,  and  at  the  same  time 
give  a  clear  outline  of  the  root.  A  fairly  hard  and  tough  wax  is 
indicated.  The  writer  has  for  many  years  used  pink  paraffin  and 
wax  for  this  purpose.  This  wax  is  moulded  in  the  form  of  a  cone, 
of  about  the  size  and  shape  shown  (Fig.  171). 

Plaster-of-Paris  moulds  may  readily  be  made,  in  which  to  cast 
these  cones,  and  it  is  well  to  prepare  a  number,  and  keep  them  on 
hand  for  use  as  needed.  The  cones  are  used  nearly  full  hard,  being 
warmed  slightly  by  holding  in  the  hand  for  a  moment  before 
using.  The  point  of  the  cone  is  then  placed  in  the  center  of  the 
root  (Fig.  172),  holding  it  in  place  with  the  thumb.  Pressure  is 
gradually  applied  and  as  the  cone  softens  slightly  from  the  heat 
of  the  mouth,  the  wax  is  spread  out  over  the  stump,  and  the  tissues 
are  forced  away  from  around  the  margin  of  the  root  (Fig.  173). 
This  is  necessarily  somewhat  painful,  but  it  does  not  last  long, 
and  the  patient  never  objects.  After  it  has  been  jjressed  up  as 
far  as  necessary,  it  is  removed.  By  this  means  a  clear  sharp  impres- 
10 


146 


BUILDING   UP  BROKEN-DOWN  ROOTS 


sion  of  the  outline  of  the  root  can  be  obtained,  even  though  it  be 
decayed  far  below  the  alveolar  border  (Fig.  174).  The  model  is 
now  made  from  this  impression. 

Preparing  the  Models. — ^The  model  can  be  made  of  oxyphosphate 
of  zinc  if  so  desired,  but  one  made  of  hard  plaster  will  answer 
every  purpose.  The  plaster  is  mixed  very  thick,  the  impression 
is  moistened,  a  little  of  the  plaster  placed  on  it  and  jarred  carefully 
in  place.  This  must  be  done  carefully,  so  as  to  make  sure  that  the 
fine  lines  will  be  reproduced.  After  the  plaster  has  well  hardened, 
the  impression  is  separated  from  it  and  the  model  is  thoroughly 
dried  out.  It  is  then  trimmed,  great  care  being  used  not  to  break 
the  thin  edges,  representing  the  thin  edges  of  the  root,  while  follow- 
ing the  outline,  and  cutting  parallel  with  the  sides  of  the  root  to 


Fig.  174 


Fig.  175 


Fig.  176 


Fig.  177 


Fig.  178 


about  one-sixteenth  of  an  inch  below  the  line  of  decay  (Fig.  175). 
It  is  then  soaked  in  thin  sandarac  varnish  and  again  thoroughly 
dried.  The  decay  having  eaten  deeply  into  the  center  of  the  tooth, 
the  edges  of  the  stump  are  very  frail  (Fig.  176).  To  lessen  the 
liability  of  their  breaking  while  fitting  the  band,  the  cavity  may 
be  filled  with  hard  wax  flush  with  the  edges  of  the  stump. 

The  measurement  can  now  be  taken  and  the  band  made,  fitting 
it  in  closely  at  the  constriction  between  the  two  roots,  and  trimming 
it  so  that  it  will  exactly  follow  the  outline  of  the  cavity  (Fi^.  177). 
The  edges  are  then  beveled  from  the  outside,  leaving  a  keen 
knife-edge  on  the  inside  of  the  band,  and  it  is  ready  for  the  mouth 
(Fig.  178). 

The  gum  around  the  stump  is  then  cocainized,  and  the  band 
forced  into  place,  the  sharp  edges  being  driven  between  the  root 
and  the  process,  thus  gripping  the  root  firmly. 

After  the  band  is  in  position  on  the  root,  the  canals  can  be  opened 
and  treated,  the  band,  being  firmly  fixed,  will  keep  away  the  soft 
tissues,  blood  and  moisture.  When  the  band  is  removed,  the 
stump  should  be  tightly  covered  with  hard  gutta-percha  to  keep 


CROWNING  BROKEN-DOWN  ROOTS. 


u: 


the  gum  from  crowding  over  the  face  of  the  root.  An  ordinary 
large-headed  tack  is  good  for  this  purpose,  covering  the  post  well 
with  the  gutta-percha  and  forcing  it  into  the  canal,  the  excess 
gutta-percha  being  forced  over  the  face  of  the  root  by  the  head  of 
the  tack.  The  head  can  then  be  covered  lightly  with  gutta-percha 
and  it  will  keep  in  position  for  any  desired  length  of  time. 

It  is  more  than  twenty  years  since  the  writer  first  employed  this 
method  of  crowning  such  like  roots.  It  was  feared  that  forcing 
the  band  between  the  root  and  the  process  might  cause  resorption, 
but  he  considered  the  experiment  was  well  worth  trying  and  he 
has  not  since  regretted  it.  Since  that  time,  this  has  always  been  his 
method  of  procedure  in  these  cases,  and  so  far  as  is  known  there 
has  not  been  a  single  failure.  This  method  may  be  employed  in 
nearly  all  cases  where  the  tooth  has  been  broken  or  decayed  below 
the  gum  line. 


Fig.  179 


Fig.  180 


Another  class  of  cases,  which  is  frequently  encountered,  is  where 
a  large  cavity  in  a  molar  extends  far  up  on  the  root  beyond  the 
gum  margin,  as  in  Fig.  179.  The  gum  should  be  first  cleared  from 
the  cavity.  This  can  be  done  by  lancing,  or  if  there  is  not  very 
much  soft  tissue  in  the  cavity,  trichloracetic  acid  may  be  used. 
Frequently,  the  impaction  of  food  has  kept  the  cavity  partially 
clear  of  soft  tissues,  and  it  may  be  possible  to  force  out  any 
remaining  tissue  by  packing  gutta-percha  or  cotton  tightly  into 
the  cavity,  and  leaving  it  there  until  a  subsequent  sitting. 

The  decay  is  first  entirely  removed,  and  the  cavity  prepared  so 
that  it  is  non-retentive  in  shape  (Fig.  180).  If  there  are  any 
undercuts,  they  may  be  temporarily  filled  with  gutta-percha. 
The  remaining  sides  of  the  tooth  are  trimmed  so  that  they  are 
nearl\'  parallel,  the  same  as  though  preparing  the  entire  tooth 
for  a  crown.  The  cavit\'  is  then  filled  with  a  slow-setting  cement, 
and   this   is  carefully  trimmed,  following  closely  the   sides  of  the 


148 


BUILDING   UP  BROKEN-DOWN  ROOTS 


root,  making  sure  that  the  cement  does  not  project  in  the  least, 
beyond  the  margins  of  the  cavity,  and  making  the  filhng  nearly 
parallel  with  that  part  of  the  tooth  which  remains  standing.  It 
should  be  notched  or  grooved  slightly  on  the  top  (Fig.  181). 

An  impression  of  the  stump  is  now  taken  with  the  cement  filling 
in  position.  After  the  impression  has  hardened,  it  is  removed 
from  the  mouth  (Fig.   182),  and    the    cement    filling   (Fig.    183) 


///A/^y 


Fig.  181 


Fig.  183 


removed  from  the  tooth  and  placed  in  position  in  the  impression, 
and  waxed  lightly,  as  in  Fig.  184.  The  tooth  cavity  should  be 
packed  with  gutta-percha  so  as  to  keep  it  open  and  the  margins 
clear. 

The  impression  is  now  varnished  and  a  model  of  hard  plaster 
made  from  it  in  the  usual  manner  (Fig.  185).  After  drying  out 
thoroughly,  the  model  is  trimmed  to  about  one-sixteenth  of  an  inch 


Fig.  184 


Fig.  185 


below  the  gum  line,  cutting  the  plaster  away  from  around  the 
cement  filling  to  about  the  same  depth,  thus  exposing  it  and  showing 
the  exact  outline  of  the  cavity  (Fig.  186). 

The  measurement  of  the  stump  should  be  taken  just  below 
the  gum  line.  The  band  is  made,  and  the  gingival  end  trimmed 
carefully,  so  that  it  follows  the  outline  of  the  cavity  and  covers  well 
the  line  of  decay  (Fig.  187).  The  edges  are  then  beveled.  It  is 
then  tried  in  the  mouth,  fitted  over  the  stump,  and  driven  into 


CROWNING  BROKEN-DOWN  ROOTS 


140 


place.  The  impression  and  articulation  is  then  taken,  the  model 
prepared  and  the  crown  completed  (Fig.  188),  and  after  completion, 
is  cemented  in  the  mouth.  It  will  be  found  to  cover  the  margins 
and  fit  the  root  more  perfectly  than  would  have  been  possible  to 
make  it  fit  in  any  other  way  (Fig.  189). 

Anterior  teeth,  such  as  the  centrals  or  laterals,  are  frequently 
found,  which  have  been  broken  off  as  from  a  blow,  the  fracture  on 


Fig.  187 


Fig.  188 


Fig.  189 


the  lingual  side  extending  far  below  the  gum  line  (Fig.  190).  They 
should  be  treated  in  practically  the  same  way  as  the  molars  in  the 
preceding  case.  The  stump  standing  out  of  the  gum  is  trimmed 
very  carefully  so  that  the  sides  are  parallel.  In  this  case,  much 
greater  care  should  be  exercised  to  have  these  sides  parallel  than 
where  the  whole  stump  is  standing  and  the  root  has  simply  to  be 
crowned.  The  canal  is  enlarged  and  a  post  fitted  into  it,  extending 
well  out  of  the  stump. 


Fig.   190 


Fig.  191 


Fig.  192 


It  is  understood  that  the  tissues  should  be  first  i)ressed  away 
(Fig.  191).  The  fractured  part  is  then  built  up  with  cement  to 
about  the  same  height  as  the  part  of  the  stump  left  standing  out 
of  the  gum,  care  being  taken  to  trim  close  to  the  margin  of  the 
root  and  make  the  sides  of  the  cement  filHng  parallel  to  the  stand- 
ing stump  (Fig.  192). 

1  f  ue  have  the  part  of  the  root  which  has  been  broken  of}',  it  can  be 
\)\\t  back  in  j)osition  after  removing  any  of  the  enamel  which  may 


150 


BUILDING  UP  BROKEN-DOWN  ROOTS 


adhere  to  it,  instead  of  replacing  it  with  cement.  The  impression  is 
taken  with  this  in  place,  the  same  as  with  the  molar.  The  broken 
piece  of  the  root  or  the  cement  is  then  removed  together  with  the 
post,  and  placed  in  the  impression,  and  a  model  made  in  the  man- 
ner already  described  in  treating  of  the  molar.  The  model  is  then 
trimmed,  carefully,  well  below  the  gum  margin  labially,  and  below 
the   line  of  fracture  lingually  (Fig.  193).    The  cement  and  post  are 


Fig.   193 


Fig.  194 


Fig.   195 


now  removed  and  the  labial  side  of  the  stump  cut  off  enough  so 
that  the  band  will  be  hidden  by  the  gum  (Fig.  194).  On  this  model 
the  band  is  fitted,  festooning  it  carefully  so  that  it  will  come  below 
the  line  of  fracture  lingually,  and  well  under  the  gum  on  the  labial 
side  (Fig.  195). 

If,  for  this  case,  a  Richmond  crown,  with  a  facing  and  a  gold 
back,  or  an  all  porcelain  crown  with  a  soldered  or  a  cast  base, 
is  to  be  made,  the  upper  edge  of  the  band  may  be  cut  flush  with 


Fig.  196 


Fig.  197 


Fig.  198 


the  edges  of  the  stump  lingually,  and  well  under  the  gum  labially 
and  a  floor  soldered  or  sweated  to  it.  The  post  is  next  fitted  and 
waxed  in  position  and  soldered  to  the  floor  of  the  cap  (Fig.  195). 
This  completed  cap  is  then  placed  on  the  root  in  the  mouth,  an 
impression  and  articulation  taken,  the  model  prepared  and  the 
crown  made  and  finished  in  the  usual  manner,  carrying  the  solder 
down  to  the  edge  of  the  band  on  the  lingual  side  (Fig.  196). 
Where  it  is  intended  to  use  a  facing,  building  up  the  lingual 


RELATION  OF  PROSTHODONTI A  AND  ORTHODONTIA      151 

side  with  porcelain,  the  band  and  floor  are  made  of  iridio-phitinum. 
The  band  on  the  hngual  side  should  extend  at  least  one-thirty- 
second  of  an  inch  above  the  line  of  fracture  (Fig.  197).  On  this 
side  a  floor  should  be  fitted  to  the  inside  of  the  band  over  the 
broken  face  of  the  root,  allowing  the  band  to  extend  above  it, 
but  on  the  labial  side  it  can  be  brought  over  the  top  of  the  band 
and  well  under  the  gum.  The  band  extending  above  the  floor  of 
the  cap  on  the  lingual  side  forms  a  protected  seat  in  which  porce- 
lain is  baked  so  that  there  will  be  no  thin  margins  of  porcelain 
which  would  be  liable  to  crack  and  flake  off  (Fig.  198). 

PORCELAIN.  BRIDGES. 

The  porcelain  bridge  as  advocated  by  many  dentists  some  years 
ago  has  become  nearly  obsolete.  Porcelain  is  a  fragile  material, 
it  cannot  be  made  sufficiently  strong  to  withstand  the  force  of 
mastication  without  great  depth  and  bulk  of  porcelain,  as  the 
strength  of  porcelain  is  only  in  proportion  to  its  bulk. 

Where  the  posterior  teeth  have  been  lost  it  is,  in  the  majority 
of  cases,  necessary  to  open  the  bite.  By  doing  this  the  masticatory 
force  is  greatly  increased,  and  there  is  no  porcelain  made  which 
will  withstand  the  strain,  unless,  as  before  stated,  the  bridge  is 
made  with  great  depth  and  bulk  of  porcelain,  or  the  patient  is 
wearing  a  plate  in  the  opposite  jaw. 

Taken  purely  from  an  esthetic  point  of  view%  porcelain  is  the 
ideal  material  to  use,  but  from  a  practical  standpoint,  it  is  not  so 
ideal.  A  porcelain  bridge  would  stand  better  if  it  were  a  fixed 
bridge  than  it  would  if  it  w^re  removable,  as  the  springing  which 
occurs  in  removing  and  replacing  the  appliance  will,  in  every 
case,  sooner  or  later,  cause  a  checking  of  the  body,  necessitating 
constant  repairs. 

RELATION    OF   PROSTHODONTIA    AND   ORTHODONTIA. 

Quite  frequently  when  the  services  of  an  orthodontist  has  been 
emi>loyed  the  cooperation  of  the  prothodontist  is  necessary  to 
complete  and  render  his  work  permanent.  Where  the  teeth  have 
been  regulated  in  mouths  where  some  of  the  teeth  have  been  lost, 
it  is  necessary  to  restore  these  lost  organs  by  some  rigid  fixture, 
otherwise  the  teeth  which  have  been  put  in  proper  occlusion  will 
quickly  /eturn  to  their  former  condition.     Where  such  conditions 


152  BUILDING   UP  BROKEN-DOWN  ROOTS 

exist,  there  is  no  appliance  so  far  suggested  as  satisfactory  and 
efficient  as  a  properly  constructed  bridge. 

In  a  large  number  of  these  cases  the  patient  is  too  young  to  have 
any  permanent  appliance  made  which  would  necessitate  the  devi- 
talization of  a  tooth.  Where  this  is  so  a  temporary  bridge  can  be 
made,  the  abutment  teeth  being  trimmed  only  just  enough  to  allow 
of  the  passing  of  the  band  between  them  and  the  adjoining  teeth, 
but  not  cutting  through  the  enamel. 

The  bridge  can  then  be  made  and  cemented  into  position,  and 
should  be  carefully  watched  until  the  patient  is  old  enough  to  have 
a  permanent  fixture  made.  Generally  this  is  not  advisable  until 
the  patient  has  reached  the  age  of  at  least  eighteen  years. 

There  are  many  cases  where  slight  irregularities  of  the  teeth 
brought  about  by  the  loss  or  decay  of  others  can  be,  previous  to 
crowning,  easily  and  quickly  corrected  without  employing  the 
services  of  an  orthodontist.^ 


Fig.  199  Fig.  200 

An  example  of  this  would  be  where  a  tooth,  say  a  lateral  incisor 
may  be  standing  a  little  distance  inside  of  the  arch  (Fig.  199).  It 
has  been  the  custom  with  some  dentists  to  cut  off  such  a  tooth, 
making  a  cap  for  it  and  letting  the  floor  extend  over  the  ridge  to  a 
point  in  line  with  the  labial  face  of  the  adjoining  teeth.  The  facing 
is  then  ground  in  position,  backed  and  soldered,  with  the  backing 
carried  lingually,  and  over  the  root  cap,  so  as  to  bring  the  facing 
into  proper  position,  as  in  Fig.  200.  This  is  not  good  practice  if  it 
can  possibly  be  avoided,  as  it  makes  a  weak  and  uncleanly  appliance. 

It  is  better  that  this  root  or  tooth  should  be  brought  out  in  line 
with  the  other  teeth  before  attempting  to  crown  it.  This  can  often 
be  done  in  a  few  days  with  some  little  simple  mechanical  appliance. 

One  of  the  simplest  appliances  for  this  purpose  would  be  a  piece 

'  The  writer  is  not  posing  as  an  orthodontist  and  does  not  intend  to  give  any 
advice  as  to  the  regulating  of  teeth  except  in  cases  where  the  irregularities  are  so 
slight  that  they  may  be  corrected  in  a  few  days. 


RELATION  OF  PROSTHODONTIA  AND  ORTHODONTIA      153 

of  spring  wire  attached  to  the  adjoining  cuspid  and  extending  over  a 
few  of  the  teeth  adjoining.  To  this  the  lateral  can  be  attached 
with  a  ligature  and  by  tightening  it  frequently  the  teeth  can  be 
brought  in  line  very  quickly.  If  the  crown  is  lost  a  staple  or 
hook  can  be  placed  in  the  root  and  the  ligature  attached  to 
that. 

Another  appliance,  which  can  be  quickly  and  easily  constructed 
and  which  gives  a  more  positive  pressure  than  does  the  spring  wire, 
is  made  in  two  parts.  The  first  consists  of  a  platinized  gold  bar, 
heavy  enough  to  resist  the  strain  and  long  enough  so  that  the  ends 
will  rest  on  the  adjoining  teeth.  A  hole  is  drilled  through  at  a  point 
opposite  the  lateral  which  is  to  be  moved.  The  second  part  is  a 
small  round  rod  of  the  same  metal,  one  end  of  which  is  shaped  so 
as  to  form  a  hook  and  the  other  end  having  a  thread  cut  on  it  to 
which  a  nut  has  been  fitted. 

The  rod  is  hooked  to  the  staple  or  other  fixture  in  the  lateral, 
the  other  end  passed  through  the  hole  in  the  bar  and  the  nut  screwed 
on.  By  tightening  this  nut  frequently,  the  tooth  or  root  is  quickly 
and  easily  brought  in  line  (Fig.  201). 

In  cases  where  the  space  for  a  lateral  or  a  central  incisor  is  nearly 
closed,  and  it  is  necessary  to  move  a  number  of  the  teeth  in  order 
to  make  room,  it  may  be  advisable  to  employ  the  services  of  an 
orthodontist. 


Fig.  201  Fig.  202 

Another  class  of  cases  of  slight  irregularities  which  are  very 
frequently  encountered  is  where  the  crowns  of  certain  teeth  are 
lost  and  the  adjoining  teeth  have  moved  together,  so  as  to  partially 
close  the  space  and  there  is  not  enough  room  to  insert  a  crown  of 
normal  size.  In  fact,  quite  often  the  space  may  be  narrower  than 
the  width  of  the  broken-down  root.  This  is  frequently  seen  where 
the  crown  of  a  first  or  second  bicusi)id  is  lost,  and  the  adjoining 
bicuspid  anfl  molar  has  moved  forward  so  as  to  partially  close  the 
space  as  in  Fig.  202. 

It  would  be  bufl  prac-ticc  to  place  a  crown  on  a  root,  where  these 


154  BUILDING   UP  BROKEN-DOWN  ROOTS 

conditions  exist,  without  first  forcing  them  apart  so  as  to  get  room 
enough  in  which  to  place  a  crown  of  normal  size.  This  can  be 
done  easily  and  quickly,  in  the  majority  of  cases,  even  when  none 
of  the  molars  are  missing,  without  making  any  mechanical  appliance 
at  all,  but  simply  by  wedging. 

If  the  three  molars  are  standing,  and  the  second  bicuspid  missing, 
the  first  step  would  be  to  put  a  blocking  of  wedges  tightly  between 
the  molar  and  the  first  bicuspid,  so  that  the  molars  could  not  move 
forward.  Then  begin  by  making  a  separation  between  the  second 
and  third  molars,  starting  at  first  with  as  large  a  piece  of  separating- 
rubber  as  can  be  placed  between  these  teeth.  After  they  have  been 
forced  apart,  somewhat,  the  work  of  separating  may  be  completed 
with  orangewood  wedges.  The  space  between  is  dried  out  and  a 
piece  of  well  compressed  orangewood  is  driven  in  between  the 
teeth  as  tightly  as  possible.  As  the  wood  becomes  moistened,  it 
expands  and  forces  the  teeth  still  further  apart.  This  is  repeated 
until  the  amount  of  separation  between  the  second  and  third  molars, 
added  to  that  of  the  space  of  the  first  molar  and  first  bicuspid 
will  give  sufficient  space  for  a  crown  of  normal  size. 

The  next  step  is  to  start  wedging  between  the  first  and  second 
molars,  at  the  same  time  easing  up,  as  progress  is  made,  the  separa- 
tion between  the  second  and  third  molars,  wedging  with  the  orange- 
wood until  the  second  molar  has  been  forced  back  against  the 
third. 


Fig.  20.3 

There  now  remains  only  the  one  tooth  to  be  moved  to  its  normal 
position,  the  first  molar.  This  is  moved  in  the  same  manner  as  the 
others,  by  increasing  the  size  of  the  wedges  between  the  first  bi- 
cuspid and  first  molar,  and  decreasing  those  between  the  first  and 
second  molars,  and  keeping  this  up  until  a  little  more  space  than 
is  necessary  for  a  normal  sized  crown  has  been  secured,  (Fig.  203). 
The  space  should  be  carefully  preserved  with  wedges  until  the 
root  is  prepared  and  the  crown  made,  and  in  place,  otherwise 
the  molars  would  quickly  resume  their  former  positions. 


nELATIOX  OF  PROSTHODONTTA  AND  ORTHODONTIA      155 

It  has  been  claimed  that  the  third  molars  cannot  be  forced  back 
but  with  this  the  writer  cannot  agree,  as  it  has  been  done  many 
times,  in  the  manner  stated. 

There  are  many  cases  Where  the  work  of  securing  a  separation 
can  be  done  entirely  by  the  patient,  especially  if  the  third  molar 
or  second  and  third  have  been  lost.  The  first  step  is  to  cut  an 
orangewood  stick  of  such  a  length  that  it  will  wedge  in  tightly 
between  the  bicuspid  and  the  molar,  concaving  it  a  little  at  each  end 
so  that  it  cannot  be  forced  out  bucally  or  lingually.  A  number  of 
these  orangewood  plugs  are  prepared,  each  one  a  little  longer  than 
the  others,  the  last  one  being  slightly  longer  than  the  space  which 
is  needed  for  the  crown  (Fig.  204).  They  are  numbered  1 ,  2,  3,  etc., 
beginning  with  the  shortest  which  is  numbered  1.  The  Xo.  1  plug 
is  now  forced  into  position  between  the  bicuspid  and  the  molar 
(Fig.  205).    The  others  are  placed  in  an  envelope  on  which  instruc- 


FiG.  204  Fig.  20.5 

tions  are  written,  and  given  to  the  patient,  the  instructions  stating 
that  as  soon  as  the  wedge  which  is  in  the  mouth  has  become  loosened 
somewhat,  so  that  it  can  be  moved  easily,  the  No.  2  is  put  in  position 
and  bitten  into  place.  This  is  repeated  as  soon  as  the  No.  2  is  loose, 
the  No.  3  is  forced  in  place  and  so  on  until  the  last  one  is  in.  The 
patient  is  instructed  to  return  after  the  last  plug  has  been  in  place 
for  three  or  four  days. 

It  will  be  found  that  in  the  majority  of  cases  the  teeth  can  be 
moved  for  a  considerable  distance  in  ten  days  or  two  weeks  with 
practically  no  pain  to  the  patient.  As  the  teeth  are  forced  apart 
they  are  held  perfectly  rigid,  so  that  there  is  no  movement  which 
will  keep  up  an  irritation. 

The  same  method  of  gaining  space  may  be  adopted  in  the  anterior 
part  of  the  mouth.  Many  times,  where  the  crown  of  a  tooth  has 
been  broken  away,  say  that  of  a  central,  or  where  the  central  root 
is  missing,  the  remaining  central  and  lateral  will  come  together 


156 


BUILDING   UP  BROKEN-DOWN  ROOTS 


so  that  perhaps  the  space  between  them  is  less  than  half  the  width 
of  the  remaining  central  (Fig.  206). 

In  such  a  case  a  crown  on  the  root  or  a  bridge  restoring  the  missing 
tooth  should  not  be  placed  unless  the  tooth  can  be  made  of  a  size 
corresponding  very  nearly  to  that  of  the  remaining  central.  If  a 
narrower  crown  is  placed,  one  not  nearly  as  large  as  its  mate,  it  is 
unsightly,  and  these  teeth  should  always  be  separated  so  as  to  make 
room  for  a  tooth  of  normal  size. 

This  can  usually  be  done  in  exactly  the  same  manner  as  has  al- 
ready been  described  in  speaking  of  the  bicuspid.  Sometimes  in 
forcing  the  teeth  apart  in  this  manner  there  will  be  a  tendency 
for  them  to  overlap  and  pass  each  other.  This  difficulty  can  gen- 
erally be  overcome  by  ligating. 

It  not  infrequently  happens  that  it  will  be  found  that  one  of 
these  teeth  has  been  loosened,  perhaps  from  a  blow,  which  has 


Fig.  206 


Fig.  207 


destroyed  the  bony  attachment  and  is  holding  only  by  the  gum  and 
is  laying  over  the  labial  side  of  the  adjoining  teeth.  The  remaining 
central  and  lateral  will  have  closed  in  behind  it.  For  esthetic  reasons 
the  patient  may  not  wish  to  have  the  injured  tooth  removed  with- 
out having  something  which  can  be  used  temporarily  while  the 
permanent  fixture  is  being  made  restoring  a  central  of  a  size  corre- 
sponding to  the  one  remaining. 

As  an  illustration  the  following  description  of  a  case  of  this  kind 
which  came  under  the  care  of  the  writer  will  serve. 

The  patient,  a  lady  over  fifty  years  of  age,  several  years  previous 
had  received  a  blow  in  the  mouth  which  had  loosened  the  left  central 
incisor.  The  condition  had  become  worse,  until  it  had  only  a 
slight  gum  attachment  and  the  tooth  was  practically  held  in  position 
only  by  the  lip  (Fig.  207) .  An  impression  of  the  parts  was  taken 
and  a  model  carefully  prepared.  The  cast  of  the  loose  tooth  was 
then  cut  from  the  model  (Fig.  208)  and  the  model  separated  by  saw- 


RELATION  OF  PROSTHODONTIA  AND  ORTHODONTIA      157 

ing  through  between  the  remaining  central  and  the  lateral.  The 
hahes  of  the  model  were  then  forced  slightly  apart  and  a  tooth, 
matching  the  other  central  in  shade,  was  ground  to  fit  in  this  space 
and  the  outer  edges  slightly  beveled  lingually.  A  thin  backing 
was  then  fitted  to  the  lingual  side  of  the  facing  extending  beyond 
it  mesially  and  distally  and  this  extension  burnished  over  the  lin- 
gual side  of  the  adjoining  central  and  lateral  (Fig.  209).    This  was 


Fig.  208 


Fig.  209 


then  waxed  and  invested  and  covered  over  with  solder.  The  model 
was  then  separated  a  little  farther  and  another  and  larger  facing 
ground  in  place  and  backed  and  prepared  in  the  same  manner.  A 
third  and  fourth  facing  were  prepared  the  same  as  the  others,  the 
last  of  which  was  as  wide  or  a  little  wider  than  the  space  required. 
The  teeth  with  the  backings  were  made  in  such  a  way  that  they 
would  wedge  between  the  central  and  lateral  but  could  not  be 
forced  either  labially  or  lingually  (Fig.  210,  a  and  h). 


Vui.  210 


The  patient  was  then  sent  for,  the  loose  tooth  removed  and  the 
smaller  of  the  backed  facings  was  forced  in  between  the  central 
and  lateral.  The  i)atient  was  then  given  some  narrow  linen  tape 
and  was  instructed  that  as  soon  as  the  ap])liance  had  loosened  a 
little  to  put  a  thickness  of  the  tape  between  the  sides  of  the  appliance 
and  the  adjoining  teeth,  and  to  keep  this  up  until  there  were  three 
or  four  thicknesses  in  place,  and  then  wear  it  until  the  piece  became 
slightly  loose  again. 

In  the  meantime,  the  work  of  devitalizing  the  adjoining  teeth 


158  BUILDING   UP  BROKEN-DOWN  ROOTS 

and  preparing  them  for  a  bridge  had  been  progressing.  As  soon  as 
the  smaller  appliance  had  forced  the  teeth  apart,  so  that  it  was  loose 
when  worn  with  several  thicknesses  of  tape,  the  second  appliance 
was  put  in  and  the  same  directions  given  regarding  the  tape.  After 
that  had  served  its  purpose  the  third  and  then  the  final  appliance 
was  put  in  position  and  worn  until  the  permanent  fixture  was  ready 
to  be  put  in  position. 

Tube  and  inlay  attachments  were  used  in  this  case,  and  the 
bridge  made  to  fill  the  space,  the  temporary  appliances  being  worn 
in  the  meantime,  and  discarded  only  when  the  bridge  was  ready 
for  the  mouth.  This  made  an  easy  and  certain  way  of  getting  the 
needed  separation,  and  during  which  time  the  patient  was  spared 
the  disfigurement  which  would  have  been  caused  by  an  ordinary 
separation,  and  only  those  intimately  acquainted  with  her  knew 
that  there  was  a  tooth  missing. 


CHAPTER  IX. 
PROSTHESIS. 

AUTOGENOUS  SOLDERING,   OR  THE  "SWEATING  PROCESS," 
AND  SOLDERING. 

There  are  two  methods  in  use,  where  constructing  crown  and 
bridge-work,  for  the  making  of  caps  and  bands,  or  uniting  pieces  of 
gold  of  the  same  carat.  First,  that  of  melting  or  welding  the  parts 
together  without  the  use  of  solder  and  which  is  known  as  the  "  sweat- 
ing process,"  or  to  use  a  more  scientific  term,  "autogenous  solder- 
ing." And  second,  soldering,  by  the  use  of  alloys  a  trifle  more  fusible 
than  the  metals  to  be  united,  fused  between  and  over  the  surfaces 
to  be  joined,  uniting  them  firmly  together.  These  alloys,  termed 
solders,  may  be  of  various  grades  of  fineness,  or  be  of  the  same  grade 
and  yet  vary  a  great  deal  in  point  of  fusibility.  These  variations 
depend  upon  the  kind  and  quantity  of  alloy  used.  As  a  rule,  the 
higher  the  carat,  or  the  nearer  the  fusibility  of  the  solder  approaches 
that  of  the  plate,  the  stronger  will  be  the  union.  The  higher  the 
fusing  point  of  the  solder  the  less  alloy  it  contains,  or  the  alloy  used 
is,  in  character,  more  like  the  plate. 

Autogenous  soldering,  or  sweating,  at  its  best,  makes  by  far  the 
strongest  union.  Its  chief  merit  in  crown  and  bridge-work  is  that  it 
is  not  re-fused  in  subsequent  solderings.  In  favorable  positions,  with 
a  little  practice,  the  art  of  autogenous  soldering  is  easily  acquired, 
and  the  union  is  very  satisfactoy.  It  requires,  however,  a  steady 
hand,  a  good  blowpipe  well  managed,  and  a  fair  degree  of  "knowing 
how,"  that  can  be  acquired  by  practice  only,  to  so  heat  two  pieces 
of  metal  that  the  surfaces  in  contact  are  fused  while  the  body  is 
near  to  but  not  actually  at  its  fusing  point.  I'nder  these  conditions 
there  seems  to  be  a  molecular  attraction  between  the  fused  surfaces 
and  they  Hcnv  together  and  unite.  A  little  less  heat,  and  the  opera- 
tion is  a  failure,  a  little  too  much,  and  the  appliance  is  ruined. 
The  real  secret  of  success  is  in  knowing  how  far  to  go,  and  when  to 
.stop.  When  once  the  "knack"  is  acquired,  it  is  surprising  how 
seldom  "just  right"  is  missed,  and  how,  as  one  advances  in  experi- 
ence, quickly  and    with   certainty  complicated  pieces  are  united 

(159) 


160 


PROSTHESIS 


by  the  sweating  method.     In  fact  it  is  more  quickly  and  easily 

done  and  with  less  liability  of  burning  than  where  solder  is  used. 

When  a  band  has  been  joined 
by  this  method,  there  has  been 
a  molecular  change  in  the  metal 
so  united  which  renders  it 
somewhat  of  the  nature  of  cast 
gold.  It  has  not  the  same 
tenacity  and  strength  at  that 
point  unless  it  has  been  well 
overlapped.  In  order  to  over- 
come this  weakness  and  bring 
about  a  rearrangement  of  the 
molecules,  the  band  is  placed 
over  the  beckhorn  of  an  anvil 
with  the  seam  uppermost,  and 
the  seam  is  hammered  until  it 
is  of  the  same  thickness  as 
the  rest  of  the  band,  and  has 
become  entirely  obliterated. 
This  forging  condenses  the 
gold  and  restores  its  tenacity, 
and  makes  the  band  practi- 
cally seamless,  and  as  strong 
where  it  has  been  joined  as  at 
any  other  point. 

Flattening  the  seam  or 
stretching  a  band  may  be 
done  as  well  by  compressing 
it  between  the  beaks  of  a 
powerful  pair  of  pliers  which 
were  designed  by  the  author 
for  this  purpose  and  are  known 
as  "stretching  and  contouring 
pliers"  (Fig.  211). 

Another  advantage   of   the 
sweating  process  is  that  the 
Pig.  211  seam  or  joint  will  not  discolor 

after  the  appliance  has   been 

worn  in  the  mouth  for  some  time,  as  does  a  seam  or  joint  made 

with  solder. 


AUTOGENOUS  SOLDERING,  OR  SWEATING  PROCESS    161 

Another  point  in  favor  of  the  sweating  process  is  that  a  cap  or 
a  crown  bnilt  up  by  sohlering  and  used  as  an  abutment  for  a  bridge, 
is  much  more  easily  burned  in  any  subsequent  resoldering  opera- 
tions to  which  it  may  be  subjected  than  is  a  sweated  crown.  The 
reason  for  this  is  very  simple  and  should  be  understood  by  every 
one  doing  metal  work. 

In  using  solder,  the  surface  of  the  gold  to  which  the  solder  is 
applied  becomes  alloyed,  the  depth  to  which  this  alloy  extends 
depending  upon  the  carat,  the  character,  the  amount  of  solder  used 
and  also  the  amount  of  heat  to  which  the  mass  has  been  subjected 


Fig.  212  Fig.  213 

in  melting  the  solder.  The  carat  of  the  gold  has  thus  been  lowered, 
sometimes  to  the  entire  depth  of  the  thickness  of  the  band.  The 
result  is,  that  in  such  a  band,  we  have  already  a  much  lower  carat 
at  the  point  of  union  than  we  had  at  the  beginning  and  far  greater 
care  must  be  exercised  in  any  subsequent  solderings  with  the  con- 
sequent greater  danger  of  burning  the  band. 

If  solder  is  used  for  uniting  the  bands  and  caps,  it  should  be  used 
in  small  quantities,  and  of  as  high  a  carat  as  the  gold  will  stand. 


Fig.  214  Fig.  215 

This  can  easily  be  of  the  same  carat  as  the  band,  as  solder  will  fuse 
at  a  lower  temperature  than  plate  of  the  same  carat.  Thus,  22 
carat  solder  can  be  used  in  soldering  22  carat  plate.^ 

When  j)rcj)ariiig  a  band  for  soklering,  it  is  optional  whether  to 
unite  the  ends  by  an  abutted  joint,  or  by  lapping  them  one  over  the 
other.  An  abutted  joint  is  not  as  strong  as  one  lapped.  It  is  also 
more  difficult  to  bring  the  al)utted  ends  into  i)erfect  contact  and 

'  T\u:  carat  of  K"1<1  dcpond.s  upon  the  quantity  of  alloy  only.  The;  fusing  point 
ui>on  thr;  ijuantity  and  character  of  the  alloy.  Any  carat  may  be  high  fusing  or  low 
fiiHing. 

II 


162 


PROSTHESIS 


hold  them  so  while  uniting  them  than  it  is  to  adjust  and  hold  in 
contact  the  ends  of  a  band  with  a  lapped  joint.  However  close  an 
abutted  joint  may  be,  the  parts  are  not  in  actual  contact,  and  after 
it  has  been  sweated  together,  it  will  be  really  a  little  thinner  at 
that  point,  than  the  band  was  originally  (Fig.  212)  thus  weakening 
it  somewhat. 

In  making  a  lapped  joint  there  is  no  necessity  for  beveling  more 
than  one  end  of  the  band.  The  beveled  end  is  brought  around 
and  under  the  end  which  has  not  been  beveled,  sufficiently  far  to 
well  overlap  it,  as  shown  in  Fig.  213.  Then,  the  overlapping  end  is 
brought  back  a  little,  and  pressed  downward  under  the  other 
(Fig.  214)  so  that  when  it  is  again  restored  to  its  proper  position 
the  elasticity  of^  the  metal  wdll  hold  the  two  ends  in  close  over- 
lapping contact. 


Fig.  216 


The  joint  is  then  sweated  together,  melting  the  overlapping 
edge  well  down  (Fig.  215).  The  joint  is  next  hammered  on  the  anvil 
beak,  or  flattened  with  the  stretching  pliers  until  the  seam  on  the 
inside  has  been  entirely  obliterated. 

Several  different  flames  may  be  used  in  the  sweating  process, 
usually,  however,  after  one  has  mastered  the  principles  involved, 
the  details  become  a  personal  matter,  and  are  modified  to  suit  the 
operation. 

After  the  ends  of  the  band  have  been  brought  into  contact  and 
fluxed,  it  is  placed  with  the  lapped  edge  uppermost  on  a  piece  of 
charcoal.  An  asbestos  block  may  be  used,  but  it  is  not  as  good  as 
the  charcoal.     Charcoal  is  cleaner,  and  reflects  the  heat,  which 


CLEANSING  GOLD  AFTER  ANNEALING  OR  SOLDERING     1G3 

materially  aids  in  the  operation.  The  blowpipe  is  employed,  using 
a  small  brush  flame  until  the  band  is  brought  to  a  red  heat,  almost 
to  the  point  of  fusing.  As  it  begins  to  glisten,  showing  that  the 
surface  is  nearly  ready  to  fuse,  the  flame  is  shortened  to  about 
from  an  inch  to  an  inch  and  a  quarter  in  length  and  passed  slowly 
along  the  joint,  using  the  inner  point  of  the  blue  flame,  until  it  is 
perfectly  united  along  its  whole  length  (Fig.  216). 

Another  method  is  to  sweat  the  parts  together  entirely  with 
the  brush  flame.  The  band  is  placed  in  the  same  position  on  the 
charcoal  as  in  the  previous  method,  and  the  large  brush  flame  is 
applied,  holding  it  on  the  band  until  it  begins  to  fuse.  As  soon  as 
the  parts  are  united,  the  flame  is  quickly  removed. 


Fig.  217 

Still  another  method  is  to  invert  the  band,  having  the  seam  down- 
ward. It  is  then  caught  lightly  with  a  pair  of  soldering  pliers  and 
held  in  the  Bunsen  flame  and  watched  carefully  until  the  gold 
is  seen  to  melt  when  it  is  quickly  withdrawn  (Fig.  217).  The  joint 
is  then  hammered  on  the  beckhorn  of  the  anvil  obliterating  the  seam. 
This  later  method  is  perhaps  easier  than  are  the  others  and  will 
probably  be  favored  by  the  majority  of  those  doing  this  work. 


CLEANSING  GOLD  AFTER  ANNEALING  OR  SOLDERING. 

A  .'>()  per  cent,  solution  of  sulphuric  acid,  technically  termed 
"jjicklc,"  is  user!  for  cleansing  tlic  surface  of  gold  after  anneahng 


164  PROSTHESIS 

and  for  removing  the  oxidation  and  fused  flux  after  soldering. 
This  acts  without  heat  if  given  sufficient  time;  it  is  usual,  how- 
ever, to  keep  the  pickle  in  a  porcelain  evaporating  disk  mounted  so 
that  it  can  be  boiled,  to  hasten  the  operation.  There  is  always 
more  or  less  unpleasant  fumes  given  off  by  the  acid,  especially 
when  it  is  boiled.  Where  much  work  is  done  it  is  best  to  provide 
a  hood  or  small  closet  with  a  door  which  can  be  tightly  closed,  and 
with  a  vent  to  the  outside  of  the  building  to  carry  off  the  fumes,  in 
which  to  keep  the  acid.  Small  pieces  can  be  boiled  in  a  test  tube 
more  conveniently  than  in  the  dish,  they  are,  however,  very  fragile, 
the  work  must  be  allowed  to  slide  in  gently,  if  dropped  in  the  tube 
will  in  all  probability  be  broken. 

Dilute  hydrochloric  or  muriatic  acid  is  also  used  for  cleansing 
the  gold.  It  does  the  work  equally  well,  but  should  never  be  used 
except  in  a  tightly  closed  closet  as  the  fumes  are  most  corrosive 
and  if  left  exposed  will  quickly  ruin  all  the  steel  instruments 
in  a  laboratory. 

It  is  desirable  to  have  at  hand  a  solution  of  bicarbonate  of  soda 
in  which  to  rinse  work  taken  from  the  pickle,  especially  if  it  is  to 
be  immediately  fitted  in  the  mouth.  It  promptly  neutralizes  the 
unpleasant  acidity  of  the  pickle. 

When  annealing  small  pieces  of  gold,  or  cleansing  bands  or 
shell  crowns  preparatory  to  soldering,  they  may  be  brought  to  a 
red  heat  and  then  plunged  into  the  cold  pickle,  but  where 
porcelain  is  present  it  is  necessary  to  boil  the  work. 

A  saturated  solution  of  alum,  used  boiling,  is  quite  satisfactory 
for  pickling,  and  very  much  more  pleasant  to  use,  although  not 
quite  as  convenient,  as  it  must  always  be  boiled.  It  may  be  kept 
in  a  narrow  lipped  pitcher,  and  when  required  for  use  sufficient 
to  well  cover  the  work  poured  into  a  porcelain  or  copper  dish 
in  which  it  may  be  boiled.  When  the  work  is  clean,  the  alum 
solution  is  poured  back  into  the  pitcher  and  the  work  rinsed  with 
water  while  still  in  the  dish.  The  alum  solution  is  not  corrosive, 
as  is  the  acid,  and  is  not  destructive  to  clothing,  etc.,  if  spilled. 

GOLD  ALLOYS  USED  FOR  MAKING  BANDS  AND  CROWNS. 

The  gold  alloy  used  for  making  bands  and  crowns  should  be 
sufficiently  pliable  to  permit  its  accurate  adaptation  to  the  stump 
or  root,  and  at  the  same  time  should  be  hard  enough,  and  possessed 
of  sufficient  tensile  strength  so  that  there  will  be  no  liability  of  its 


RELATIVE  MERITS  OF  CROWNS  1G5 

stretching  out  of  shape,  and  so  defeating  the  object  for  which  the 
band  was  designed.  It  should  also  be  of  a  sufficiently  high  carat 
to  withstand  the  oral  secretions. 

An  alloy  of  gold  and  silver  is  more  easily  adapted  than  is  a 
harder  alloy,  but  is  too  soft  to  give  the  best  results,  especially 
for  crowns  used  as  anchorages  for  bridge-work.  A  tight  fitting 
band  of  this  alloy  driven  over  a  stump  is  likely  to  become  buckled 
and  distorted.  A  gold  alloy  possessing  the  properties  of  American 
gold  coin  as  regards  strength,  rigidity  and  elasticity,  is  more  suit- 
able for  this  purpose  than  is  the  ordinary  twenty -two  carat  gold 
of  the  dental  depots. 

Although  coin  gold  is  somewhat  more  difficult  to  manipulate 
than  is  the  other,  it  will  make  a  far  stronger  and  more  lasting 
band  or  crown,  and  is  much  to  be  preferred,  especially  if  the  band 
or  crown  is  used  as  an  abutment  for  a  bridge. 

The  copper  in  coin  gold  gives  it  a  deeper  color  than  has  the 
same  carat  with  a  large  proportion  of  silver  in  the  alloy.  Some 
object  to  it  for  this  reason,  but  the  w'riter  prefers  the  deep  rich 
reddish  color  of  the  coin  rather  than  the  light  lemon  color  of  the 
twenty-two  carat  gold  plate  of  the  dental  depots.  There  is  very 
little  difference  in  the  carat  of  the  two  alloys,  the  coin  being  21,6 
carat,  or  900  fine,  and  the  other  22  carat,  or  910  fine. 

RELATIVE    MERITS    OF    SWAGED    SEAMLESS     CROWNS    AND 
BUILT  UP  CROWNS  WITH  SOLID  GOLD  CUSPS. 

There  have  been  a  number  of  outfits  placed  on  the  market  for 
making  of  seamless  gold  shell  crowns.  Some  are  more  elaborate 
than  others,  but  there  seems  to  be  very  little  difl'erence  in  the 
quality  of  the  work  done  by  these  different  devices. 

The  seamless  shell  crown  does  not  meet  the  writer's  approval. 
It  must  be  made  of  a  soft  metal,  and  therefore  it  possesses  very 
little  strength,  and  should  be  used  only  as  a  temporary  appliance. 

In  making  these  crowns,  the  metal,  at  every  part  except  at  the 
gingival  edge,  is  stretched  during  the  operation  of  contouring  and 
forming  the  cusps,  so  that  the  metal  necessarily  becomes  very 
much  thinner  than  it  originally  was,  and  this  is  especially  true  of 
the  metal  on  the  occlusal  surface  of  which  the  cusps  are  formed. 

Many  of  these  crowns  are  cemented  in  position  without  any 
reinforcement  of  the  occlusal  surfaces,  with  the  result  that  within 
a  very  short  time  they  are  worn  through,  the  cement  is  disinte- 


166  PROSTHESIS 

grated,  and  the  operation  soon  becomes  a  wreck.  It  should  be 
a  general  custom,  when  these  crowns  are  used,  before  cementing 
them  in  place,  to  flow  solder  into  the  caps,  filling  the  cusps  well  so 
as  to  stifi^en  them  and  enable  them  to  withstand  the  strain  and 
wear  of  mastication. 

It  not   infrequently   happens  that  in  contouring  and  in  form- 
ing the  cusps,  that  the  gold  is  over-strained,  and  there  will  be 
minute  cracks  in  the  fissures   which  extend  entirely 

lllpll,        through  the  gold,  but  are  so  minute  as  not  to  be  noticed. 

rlBIBl        ^^  flowing  the  solder  into  the  cusps,  it  is  rarely  that 

|m|||H)        it  will  overflow  the  fissures  which  are    the    highest 

points  in  the  inverted  cusps,  but  it  will  always  drop 

Fig.  218        {^to  the  cusps  which  are  the  deepest  part  of  the  crown 
(Fig.  218). 

When  cemented  in  place,  the  crown  may  protect  the  tooth  for 
a  time,  but  the  moisture  and  fluids  of  the  mouth  will  be  carried 
through  these  cracks  in  the  fissures,  disintegrating  the  cement, 
causing  decay  and  many  times  the  tooth  is  entirely  ruined  before 
the  patient  is  aware  that  there  is  any  thing  the  matter  with  it,  the 
same  as  when  the  cusps  have  been  ground  through. 

This  very  often  happens  where  a  crown  of  this  type  is  used  for 
an  attachment  for  a  bridge,  another  abutment  perhaps  holding 
the  bridge  in  place  so  that  the  patient  is  not  conscious  of  any 
change  which  may  take  place  until  it  is  too  late  to  save  the  tooth. 

Another  objection  to  this  crown  as  an  attachment,  aside  from 
the  possible  defects  already  mentioned  is  that  a  crown  of  this 
type  is  not  of  suflficient  strength  to  give  support  to  a  bridge. 
Being  made  of  such  thin  and  soft  material,  if  there  is  much  stress 
on  the  bridge,  the  side  of  the  crown  is  frequently  torn  out  at  the 
point  where  the  dummies  are  united  to  it,  and  the  whole  piece  is 
rendered  useless. 

Again,  if  the  crown  is  made  to  fit  the  stump,  accurately  contoured 
as  it  should  be  contoured,  and  carefully  articulated,  it  will  take  a 
much  longer  time  to  make  it  with  any  of  the  seamless  crown  ap- 
pliances that  are  on  the  market  than  it  would  to  make  an  accurately 
contoured  and  solid  cusp  built-up  crown,  while  there  can  be  no 
comparison  as  to  the  strength  and  lasting  qualities  of  the  two 
crowns. 

As  before  stated,  these  crowns  may  be  used  for  a  temporary 
protection  of  the  natural  crown  of  the  tooth,  but  should  not  be 
considered  in  permanent  work. 


HOW  TO   USE   THE  SHEARS  IN  FESTOONING  A   BAND     167 

HOW  TO  USE  THE  SHEARS  IN  FESTOONING  A  BAND. 

In  festooning  a  band,  the  flat  side  of  the  scissors  or  the  inside  of 
the  blade  should  always  be  placed  next  to  the  band.  If  cutting 
to  an  outside  mark,  the  edge  which  is  being  trimmed  should  be  to 
the  left,  the  flat  of  the  scissors  placed  against  the  edge  and  cutting 
from  the  top  of  the  band,  as  in  Fig.  219. 


Fig.  219 


If  cutting  to  an  inside  mark,  as  where  the  inside  of  the  band 
has  been  scribed  around  the  top  of  the  stump,  this  edge  of  the 
band  should  be  turned  to  the  right,  placing  the  flat  of  the  scissors 
on  the  lower  side  and  following  the  marks  (Fig.  220). 

If  the  outside  of  the  blade  is  placed  against  the  metal,  it  will  be 
impossible  to  festoon  it  without  distorting  the  band. 

Fig.  221  shows  curved  crown  shears. 

Fig.  222  shows  straight  crown  shears. 


168 


PROSTHESIS 


Fig.  220 


Fig.  221 


Fig.  222 


HOW   TO   USE  THE  SHEARS  IN  FESTOONING  A   BAND     169 

Characteristics  of  the  Cusps  of  Upper  and  Lower  Bicuspid  and 
Molar  Teeth. — In  making  a  selection  of  cusp  buttons  or  moulds 
to  serve  as  models  from  which  to  make  the  occlusal  face  of  bicuspid 
and  molar  crowns  or  in  carving  the  cusps  it  is  important  to  have 
a  general  idea  of  the  characteristic  or  typical  form  of  the  cusps 
of  the  natural  bicuspid  and  molar  teeth.  Although  there  are 
slight  variations,  each  normal  tooth  has  certain  characteristic 
markings,  or  cusp  forms,  which  indicate  at  a  glance  the  position 
it  should  occupy  in  the  mouth.  These  will  now  be  considered; 
they  should  be  borne  in  mind  when  selecting  the  model  for  or 
carving  the  cusps  of  bicuspid  and  molar  crowns. 

Upper  First  Molars. — Looking  at  the  first  upper  molar  from  the 
occlusal  surface,  it  will  be  seen  that  it  is  diamond-shape,  the  greatest 
diameter  being  from  the  anterior  buccal  to  the  posterior  palatal 
corner  (Fig.  223),  and  also  in  the  outline  drawing  of  Fig.  226,  the 
outside  line  showing  the  outline  of  the  first  molar.  These  teeth 
have  four  cusps,  the  buccal  and  lingual  being  very  different  in 


shape  from  each  other.  The  lingual  aspect  of  the  buccal  cusps 
slope  inward  to  the  fissure  on  nearly  a  straight  line,  the  mesio- 
buccal  and  disto-buccal  cusps  being  nearly  of  the  same  size  and 
with  a  prominent  ridge  near  the  center  of  each  cusp;  the  buccal 
occlusal  points  being  fairly  sharp  (Fig.  224  a). 

The  lingual  cusps,  on  the  contrary,  are  large  and  well  rounded 
(Fig.  224  h),  the  disto-palatal  being  entirely  separated  from  the 
other  cusps  by  a  deep  fissure  extending  from  the  middle  of  the 
distal  aspect  to  midway  on  the  palatal  side  of  the  tooth  (Fig.  223). 
This  cusp  is  distinctly  different  in  shape  from  the  others  and  will 
always  indicate  on  which  side  of  the  mouth  the  tooth  belongs. 

The  Upper  Second  Molar. — In  studying  the  upper  second  molar 
closely  ( I'ig.  22.")j,  it  will  be  found,  on  looking  at  the  occlusal  sur- 
faces, that  they  are  very  nearly  of  the  same  shape  as  are  the  first 
molars,  with  the  exception  that  the  diameter  of  the  tooth  from  the 
anterior  buc(;al  to  the  posterior  j;alatal  corner  is  slightly  less  pro- 
portionately than  it  is  in  the  first  molar,  as  will  be  seen  in  the  lines 


170  PROSTHESIS 

in  the  drawing  (Fig.  226),  the  middle  line  in  the  posterior  palatal 
corner  representing  the  outline  of  the  second  molar.     It  is  also  to 


Fig.  225  Fig.  226 

be  noticed  that  the  disto-palatal  cusp  is  smaller  and  not  so  well 
defined  as  it  is  in  the  first  molar. 

The  Third  Molars. — With  the  third  molar  where  there  is  the  normal 
number  of  roots,  will  be  found  the  same  general  shape  prevailing 
as  in  the  other  molars  (Fig.  227),  but  in  the  third  molar  the  diameter 
of  the  tooth  from  the  anterior  buccal  to  the  posterior  palatal  is 
still  further  decreased,  and  in  many  cases  will  be  found  to  be  less 
than  the  disto-buccal  to  the  anterior  palatal  (Fig.  226),  the  inner 
line  at  the  posterior  palatal  corner  showing  the  outline  of  the 
third  molar.  The  disto-palatal  corner  also  is  still  further  rounded 
so  that  the  occlusal  end  of  the  tooth  frequently  presents  a  trian- 
gular or  rounded  appearance  rather  than  the  typical  diamond- 
shape.    Often,  too,  the  disto-palatal  cups  will  have  almost  entirely 


Fig.  227  Fig.  228  Fig.  229 

disappeared,  but  still  in  nearly  every  case,  there  is  to  be  found 
some  trace  of  it,  and  the  cusps  may  appear  simply  in  rudimentary 
form  on  the  disto-palatal  corner  of  the  tooth,  below  the  line  of 
the  other  cusps,  as  in  Fig.  228.  It  is  very  rarely  that  all  traces 
of  it  are  absent. 

Where  a  number  of  upper  molar  cusp  buttons,  both  for  the 
right  and  the  left  side  have  been  mixed  together,  they  can  readily 
be  distinguished  and  separated  by  placing  them  on  the  table  cusp 
up,  and  with  the  buccal  side  toward  the  viewer.  Take  note  of  the 
disto-palatal  cusp,  and  whichever  way  that  points,  whether  to 
the  right  or  the  left,  the  cusp  is  for  that  side  of  the  mouth  (Fig. 
229).  A  knowledge  of  this  fact  facilitates  very  much,  not  only 
the  separation  of  the  cusp  buttons  of  the  right  side  from  those 
of  the  left,  but  the  character  of  the  palatal  cusp,  together  with 


HOW  TO   USE  THE  SHEARS  IN  FESTOONING  A   BAND     171 


the  general  outline  of  the  crown,  will  indicate  whether  it  be  the 
first,  second  or  third  molar. 

Lower  Molars. — In  the  lower  molars,  the  shape  of  the  crown 
of  the  tooth  is  very  different  from  that  of  the  uppers.  Viewed 
from  the  occlusal  surface,  it  is  in  the  form  of  a  parallelogram,  the 
mesio-distal  diameter  being  much  greater  than  the  bucco-lingual. 
It  is  also  frequently  slightly  broader  at  the  mesial  side  than  at  the 
distal  (Fig.  230).  ' 

Lower  First  Molar. — The  lower  first  molar  has  five  cusps  and  in  this 
instance  we  ha\e  the  reverse  of  the  upper  molar,  the  sharper  cusps 
being  the  lingual  (Fig.  231  a)  and  the  broad  and  rounded  cusps  being 
the  buccal  (Fig.  231  b).     This  must  of  necessity  be  the  case  in  order 

b  a 


Fig.  230 


Fig.  231 


that  there  may  be  a  perfect  occlusion,  as  in  Fig.  232.  On  the 
buccal  side  there  are  three  cusps,  the  mesial  cusp  and  the  middle 
cusp  being  the  larger.  The  fissure  between  these  two  is  a  little 
anterior  to  the  center,  while  the  distal  cusp  is  the  smallest  of 
the  three,  the  fissure  extending  generally  from  about  one-sixteenth 
of  an  inch  from  the  disto-buccal  side  of  the  tooth  diagonally  toward 
the  center  (Fig.  233). 


Fig.  232 


Fig.  234 


The  anterior  sulci  will  be  found  fairly  close  to  the  mesial  face  of 
the  tooth,  being  broad  and  extending  buccally  and  lingually  across 
al)out  one-third  to  one-half  of  the  width  of  the  tooth.  Distal ly 
the  fissure  is  forked,  one  branch  separating  the  middle  and  distal 
cusp  and  the  other  reaching  in  an  oi)iK)site  direction  toward  tlie 
lingual  side  of  the  tooth.  The  shape  of  the  cusps  and  the  character 
of  the  fissure  are  the  distinguishing  marks  of  these  teeth. 


172  PROSTHESIS 

Lower  Second  Molars. — In  the  second  molar,  there  are  but  four 
cusps,  the  two  sharper  cusps  lingually,  the  two  buccal  cusps  being 
broad  and  rounded  and  of  nearly  equal  size.  This  also  has  the 
broadened  fissure  in  the  anterior  part  of  the  cusp,  the  same  as 
the  first  molar  and  also  the  fissure  is  forked  distally,  the  structure 
between  the  fork  forming  a  rudimentary  fifth  cusp  in  the  middle 
of  the  distal  side  of  the  tooth  (Fig.  234). 

Lower  Third  Molars. — With  the  third  molars  or  wisdom  teeth, 
the  crown  is  generally  smaller  and  narrower  than  are  the  other 
two  molars.  The  cusp  may  be  similar  in  character  to  the  second 
molar,  but  this  tooth  is  subject  to  a  much  greater  variation  than 
are  the  other  two,  and  in  fact  at  times  the  character  and  arrange- 
ment of  the  cusps  are  entirely  different  not  only  from  any  other 
tooth  in  the  mouth,  but  from  any  other  human  tooth. 

The  difference  between  the  rights  and  lefts  in  the  molars  of  the 
lower  jaw  is  not  so  marked  as  it  is  in  the  case  of  the  upper,  and 
occasionally  it  is  so  slight  that  they  may  be  used  interchangeably. 
This  is  especially  true  if  it  is  desirable  to  cross  the  bite  so  that  the 
lower  molars  will  bite  outside  the  upper  rather  than  on  the  inside. 
In  this  case,  the  cusp  of  a  right  lower  molar  may  be  used  on  the  left 
side  or  that  of  a  left  may  be  used  on  the  right,  so  as  to  bring  the 
broad  buccal  cusp  on  the  lingual  side,  thus  giving  a  broader  occlusal 
surface. 

Again,  the  cusp  might  be  reversed  end  for  end  so  as  to  secure  a 
better  occlusion,  and  then,  after  a  little  carving,  it  can  be  made 
to  represent  the  tooth  which  is  being  reproduced. 

This  interchangeability  will  very  rarely  work  in  the  case  of  an 
upper  molar.  It  should  be  remembered  in  this  connection,  that  the 
one  thing  for  which  the  operator  is  working  is  to  restore  the  mouth 
to  as  nearly  a  normal  condition  as  possible,  and  in  order  to  do  this, 
it  is  absolutely  essential  to  secure  the  most  perfect  occlusion  it  is 
possible  to  obtain. 

The  Upper  Bicuspids. — In  the  upper  bicuspids,  as  the  name  implies, 
there  are  but  two  cusps,  the  buccal  cusp  being  sharp,  as  in  the  case  of 
the  buccal  cusps  of  the  upper  molars,  and  very  similar  in  character, 
while  the  lingual  cusps  are  more  rounded,  although  not  to  the 
same  extent  as  are  those  in  the  molars.  The  first  bicuspid  is  the 
larger  of  the  two,  but  the  character  of  the  cusps  of  the  two  are  nearly 
identical. 

The  Lower  Bicuspids. — The  first  bicuspid  has  a  long  sharp  buccal 
cusp,  but  there  is  very  little  in  the  way  of  a  lingual  cusp.  In  fact, 
this  tooth  often  presents  the  appearance  of  a  cuspid  with  simply  a 


CONSTRUCTING  A   CONTOURED  GOLD  CROWN  173 

rudimentary  cusp  on  the  lingual  aspect  of  the  tooth  just  above  the 
basilar  ridge  and  is  of  no  assistance  in  mastication. 

With  the  second  bicuspid,  which  is  larger  than  the  first,  the 
buccal  cusp  is  not  so  high  nor  so  sharp  as  that  of  the  first.  The 
lingual  cusp  is  broader  and  flatter  than  that  of  the  first,  and  is 
often  divided  so  as  to  form  what  might  be  called  a  tricuspid. 

Both  the  cusps  of  the  upper  and  lower  bicuspids  may  often  be 
used  interchangeably  for  either  side  of  the  mouth,  in  order  to  secure 
better  results,  and  the  character  of  the  cusps  of  the  opposite  sides 
is  so  similar  that  it  is  very  rarely  that  the  change  would  be  detected. 

CONSTRUCTING     A    BUILT    UP    CONTOURED    GOLD    CROWN 
WITH  SOLID  GOLD  CUSPS. 

Taking  the  Measurement  of  the  Root. — The  measurement  of  the 
stump  or  root  should  be  taken  straight  across  and  as  nearly  at  a 
right  angle  with  the  sides  as  possible.  It  is  very  rarely  that  this 
measurement  should  actually  follow  the  gum  line.  Where  there  has 
been  a  recession  of  the  gum  on  one  or  more  sides  of  the  tooth,  if  the 
wire  with  which  the  measurement  is  taken  is  carried  down  to  these 
points  all  around,  it  will  be  found  that  the  band,  when  it  is  made, 
will  be  too  large  to  fit  the  stump. 

As  will  be  seen  in  the  illustration  of  a  lower  molar  where  the 
tissues  are  high  at  the  back,  but  show  a  considerable  recession 
on  the  mesial  side  of  the  tooth  (Fig.  235),  if  the  measurement  is 


Fig.  235 

taken  following  the  line  of  the  gum  from  a  to  b,  when  it  is  brought 
up  .so  that  it  extends  straight  across  following  the  line  a  to  c,  it 
will  be  much  larger  than  it  should  be.  The  wire  .should  be  forced 
as  far  under  the  gum  distally  as  j)ossible  and  then  brought  straight 
acro.ss  to  the  point  d.  Then,  too,  in  Fig.  236,  showing  an  upper 
molar  with  considerable  recession  of  the  tissues  buccally  and  lingu- 
ally,  it  can  readily  be  .seen  if  the  measurement  follows  the  gum 
line  fn»m  a  to  b  that  when  it  was  .straightened  out  it  would  extend 
from  r  to  (I,  with  the  result  that  a  band  marie  to  this  measurement 
would  be  much  too  large. 


174 


PROSTHESIS 


Built  up  Shell  Crowns  with  Solid  Cusps. — A  built  up  crown,  with 
solid  cusps,  is  the  best  and  most  enduring  crown  that  can  be  made, 
whether  used  as  a  single  crown  or  as  an  abutment  for  a  bridge 
(Fig.  237).   _ 

Where  it  is  necessary  to  restore  very  much  contour  (Fig.  238), 
the  band  should  be  cut  on  a  bevel,  measuring  from  the  gingival 


Fig.  237 


Pig.  238 


edge  and  flaring  it  outward  toward  the  occlusal,  the  amount  of 
the  flare  depending  on  the  amount  of  the  contour  which  is  to  be 
given  to  the  crown  (Fig.  239).     Where  the  adjoining  teeth  have 


Fig.  239 


Fig.  240 


Fig.  241 


closed  in  on  the  stump,  and  there  is  very  little  or  no  contour  to  be 
restored,  as  in  Fig.  240,  the  ends  of  the  band  may  be  cut  parallel 
with  each  other  (Fig.  241).  If  in  this  case,  the  band  were  cut  on 
a  bevel  and  made  larger  at  the  occlusal  end,  when  forced  onto 


Fig.  242 


Fig.  243 


Fig.  244 


the  stump  it  would  be  squeezed  together  mesially  and  distally 
and  forced  out  buccally  and  lingually  beyond  the  line  of  the  adjoin- 
ing teeth  as  in  Fig.  242. 

One  end  of  the  band  is  then  beveled  to  a  knife  edge  and  the 
ends  are  brought  together  and  sweated  or  soldered.  The  band 
should  now  be  given  the  approximate  shape  of  the  tooth  which  is  to 


CONSTRUCTING  A   CONTOURED  GOLD  CROWN 


175 


be  crowned  (Figs.  243  and  244)  and  is  next  roughly  festooned  so 
as  to  follow  the  gum  line  approximately  (Fig.  245). 
The  shaping  of  the  bands  is  best  done  with  the 
collar  pliers  shown  in  Figs.  246  and  247.  The  beaks 
of  Fig.  246  are  very  narrow,  one  having  a  flat  face, 
the  other  being  rounded  and  slightly  shorter  than  the 
other.  Fig.  247  is  made  on  the  same  plan,  having 
one  flat  and  one  rounded,  but  the  beaks  are  much 
broader  than  Fig.  246.     Fig.  246  is  used  in  shaping         fig.  245 


I'n^.  24G  — Pccso  pliers. 


Fig.  247— Kobinson  pliers. 


176  PROSTHESIS 

lower  incisors  and  other  small  bands,    and    Fig.  247  for  molar, 
central  incisor  and  cuspid  bands. 

The  band  is  placed  on  a  stump  and  scribed  around  on  the  out- 
side with  a  sharp  instrument  following  the  gum  line  carefully  (Fig. 
245),  after  which  it  is  removed  and  trimmed  to  the  line  and  the 
outer  edge  bevelled  so  that  it  will  pass  under  the  gum  without  irri- 


FiG.  248. — In  using  the  file,  the  band  should  be  held  gingival  edge  up  and  filed 
from  the  inside  outward  so  as  to  throw  the  feather  edge  to  the  outside,  leaving 
the  band  smooth  on  the  inside.  The  feather  edge  is  afterward  removed  by  beveling 
the  edge  of  the  band  on  the  outside. 

tating  it.  It  is  then  replaced  on  the  stump  and  forced  well  down 
over  it.  It  is  again  marked,  and  removed  and  with  a  fine  file  accu- 
rately shaped  to  the  gum  line,  so  that  it  will  pass,  evenly,  about 
one-sixteenth  of  an  inch  beneath  the  gum  all  around  (Fig.  248). 
After  it  is  accurately  in  position  the  impression  is  taken. 

The  model  is  cast  and  prepared  as  already  described  when  treating 


CONSTRUCTING  A   CONTOURED  GOLD  CROWN  177 

of  making  models.  The  band  is  removed  by  warming  it  slightly  or 
by  grasping  it  with  a  pair  of  warm  pliers  which  softens  the  wax 
and  allows  it  to  come  away  from  the  model.  The  remaining  wax 
should  be  burned  awRv  and  the  band  cleansed  in  dilute  sulphuric 
acid.  The  wax  should  also  be  removed  from  around  the  stump 
on  the  model. 

Contouring  the  Band. — The  stretching  of  the  band  for  contouring 
may  be  done  on  the  beckhorn  of  the  anvil  or  with  the  stretching 
and  contouring  pliers  (Fig.  211)  as  previously  described.  In 
stretching  the  band,  whether  with  the  pliers  or  on  the  anvil,  it  is 
started  at  a  point  slightly  above  the  gingival  edge,  working  around 
the  banil  from  this  point  and  gradually  increasing  the  pressure 
as  the  occlusal  end  is  approached,  giving  the  band  something 
of  a  bell-shape,  until  it  is  flared  somewhat  more  than  enough  to 
give  the  required  contour  (Fig.  249). 

In  using  the  pliers,  one  beak  of  which  has  a  broad  flat  face,  while 
the  other  is  narrow  and  has  a  round  face,  the  smaller  beak  is  placed 


Fig.  249  Fig.  250 

inside  the  band  and  the  larger  flat  faced  beak  on  the  outside; 
the  stretching  is  done  by  closing  the  handles  lightly  and  working 
around  the  band,  gradually  increasing  the  pressure  as  the  work 
progresses  from  the  gingival  to  the  occlusal  end. 

The  band  is  then  annealed,  and  with  a  pair  of  Robinson  pliers 
(Fig.  247)  the  occlusal  end  is  straightened  so  as  to  give  the  desired 
broad  point  of  contact  with  the  adjoining  teeth.  The  edge  should 
not  be  tipped  inward  in  the  least,  but  the  sides  should  be  brought 
so  that  they  are  parallel  with  each  other  for  approximately  about 
one-third  the  length  of  the  band,  as  in  Fig.  250. 

If  the  band  is  simply  stretched  and  not  straightened  up  toward 
the  occlusal  end,  it  will  be  seen  by  the  illustration,  that  if  the  cusp 
was  soldered  on  and  the  crown  completed,  the  point  of  contact 
would  be  very  slight  and  the  crown  would  not  in  the  least  resemble 
the  crown  of  a  natural  tooth  (Fig.  251). 

If  the  shaping  of  the  band  is  done  with  a  pair  of  contouring  pliers, 
and  the  edge  turned  in  too  much  at  the  occlusal  end,  when  the 
12 


178 


PROSTHESIS 


cusp  is  in  place,  the  point  of  contact  will  be  below  where  it  is  united 
to  the  band,  leaving  a  groove  extending  around  the  whole  crown 
at  the  point  of  union  of  the  cusp,  giving  the  crown  something  of 
a  door-knob  effect  (Fig.  252). 

After  the  occlusal  end  of  the  band  has  been  straightened  as 
described  above,  it  is  shaped  so  as  to  bring  out  the  normal  contour 


Fig.  252 


'H,  \  - 


^-j-^ 


>3    t 


r--  c 


Fig.  254 


of  the  tooth  and  to  bring  it  in  close  contact  with  the  adjoining 
teeth  (Fig.  253).  The  occlusal  end  is  filed  perfectly  flat  and  it  is 
then  ready  for  the  cusp. 

The  Making  of  the  Cusp. — There  are  many  different  methods  of 
making  the  cusp,  any  one  of  which  may  be  indicated  in  certain 
cases.  One  method  is  to  carve  the  cusp  in  wax,  modeling  com- 
position, or  plaster.     A  fusible  metal  die  and  counter  die  is  then 


CONSTRUCTING  A   CONTOURED  GOLD  CROWN 


179 


made  and  a  matrix  of  very  thin  pure  gold,  about  three  one- 
thousandths  of  an  inch  in  thickness,  is  swaged  from  this  and 
filled  with  coin  gold  or  the  trimmings  from   the  band. 

Another  method  is  to  have  a  supply  of  cusp  buttons,  similar  to 
those  used  in  the  Hollingsworth  system  (Fig.  251).  These  buttons 
consist  of  a  thin  copper  matrix  filled  in  with  soft  solder.  There 
are  many  good  cusp  buttons  supplied  with  the  Hollingsworth 
System,  but  they  can  be  added  to  very  easily  by  the  dentist  himself, 
as  it  is  impossible  to  have  too  many  of  these  buttons. 


liii 


'     Fig.  255 

In  making  cusp  buttons  an  impression  is  taken,  and  a  model 
[>r(;par('d  of  any  cusp  which  it  is  desired  to  rej)roduce,  and  a  die 
and  ccjuntcr  die  made  of  fusible  m(;tal.  The  matrix  is  made  of  very 
thin  brusli  copper,  about  No.  .'iO-gauge,  which  can  generally  be 
obtained  at  an  electrical  supply  house.  This  is  well  annealed  and 
.swaged  between  the  die  and  counter  die,  carefully  l)urnishing  out 
any  wrinkles  which  may  appear. 


180 


PROSTHESIS 


It  may  be  necessary  to  anneal  the  copper  two  or  three  times 
during  the  operations.  After  a  perfect  matrix  has  been  obtained, 
it  is  thoroughly  cleansed.  This  may  be  done  by  heating  and 
dipping  it  in  a  50  per  cent,  solution  of  alcohol  and  water.  It  is  then 
fluxed  with  zinc  chloride  and  filled  in  with  tinner's  half  and  half 
soft  solder.  This  is  very  easily  done  by  using 
the  solder  in  the  form  of  wire.  The  margin  of 
Fig.  256  the  cusp  matrix  should  be  left  until  after  it  has 

been  filled  and  the  excess  filed  away. 
The  cusp  matrix  is  first  fluxed  with  zinc  chloride  and  then 
grasped  with  a  pair  of  pliers  and  held  over  the  flame  of  a  Bunsen 
burner,  and  the  wire  solder  fed  in  (Fig.  255),  using  enough  so  as 
to  leave  the  surface  slightly  convex  (Fig.  256),  after  which  it  is 
thoroughly  cleansed  with  water  to  wash  away  the  zinc  chloride. 
Then  the  cusp  button  is  laid  on  a  very  coarse  flat  file,  grasped  in 


Fig.  257 


the  fingers,  and  rubbed  back  and  forth,  the  extending  surplus  of 
the  copper  matrix  protecting  the  fingers  (Fig.  257),  and  the  sur- 
plus solder  is  filed  away  until  the  under  surface  is  perfectly  flat. 

After  it  is  filed  perfectly  smooth  and  flat,  the  cusp  button  is 
completed  by  trimming  and  smoothing  the  edges  (Fig.  258). 

By  having  a  large  selection  of  these  cusp  buttons,  one  can  gener- 
ally be  found  which  will  so  nearly  fit  the  case  in  hand  as  to  require 
but  slight  changes.      It  should  be  slightly  larger  than  the  band. 
If  there  are  any  points  which  need  raising  they  can 
be  built  up  with  hard  wax  and  suitably  carved. 

A  pure  gold  matrix  for  a  gold  cusp  is  made  by 

using  one  of  the  swaging  devices  to  be  procured  at 

any  dental  depot.    They  consist  of  a  base  with  a 

raised  anvil,  a  heavy  metal  tube  passing  over  the  anvil  with  a 

soft  rubber  plunger  which  fits  into  the  tube  and  over  this  a  metal 

plunger  (Fig.  259).     The  pure  gold  used  for  the  matrix  is  about 


Fig.  258 


CONSTRUCTING  A  CONTOURED  GOLD  CROWN 


181 


three  one-thousandths  of  an  inch  in  thickness.  This,  when  the 
gold  is  doubled,  will  fit  into  No.  34  Brown  and  Sharpe  gauge. 
A   piece   of  this   pure   gold,  a  little  larger   than  the  button,  is 


Vu:.  2.Vi 


annealed  and  pressed  over  the  })utton  as  it  lays  on  the  anvil 
(Fig.  259).     The   metal   cylinder   is   then    put   in  j)lace  and   the 


182 


PROSTHESIS 


rubber  dropped  into  it  on  top  of  the  pure  gold,  and  over  this 
the  steel  plunger.  The  swager  is  then  placed  on  a  large  anvil  and 
the  plunger  is  struck  a  sharp  blow  with  a  heavy  hammer.^    The 


Fig.  260 

matrix  will  be  a  perfect  reproduction  of  the  button  which  has 
been  used.     This  matrix  is  now  filled  with  coin  gold. 

Filling  the  Cusp  Matrix.— The  trimmings  of  the  band  and  other 
scraps   of  coin   gold   are  fused   into   a   button  sufficiently  large 

1  A  rawhide  hammer,  or  a  hammer  having  a  fiber  face  is  best,  as  it  will  not  mar 
the  plunger  as  does  a  steel  hammer. 


CONSTRUCTING  A  CONTOURED  GOLD  CROWN 


183 


to  fill  the  matrix.  The  matrix  is  placed  on  the  charcoal  block, 
cusp  side  down,  and  the  heated  ball  of  gold  is  placed  in  it 
and  fused  with  the  blow-pipe.  This  can  be  done  by  using 
a  brush-flame,  care  being  taken  not  to  use  more  air  than  is 
necessary  to  keep  the  flame  steady,  holding  the  blow-pipe  about 
two  and  one-half  to  three  inches  above  the  button  of  gold,  using 
a  steady  pressure  of  air,  just  enough  to  carry  the  flame  to  the 
button  and  curl  a  little  at  the  end,  as  in  Fig.  260.  The  flame  is 
flashed  oft'  for  an  instant,  if  the  matrix  becomes  over-heated,  and 


Fig.  261 


Fig.  262 


then  back  again,  repeating  this  as  may  be  necessary  until  the 
gold  is  melted  and  fills  the  matrix.  This  slow  soft  flame  will  give 
sufficient  heat  to  melt  the  coin  gold,  but  not  the  pure  gold  matrix, 
which  has  a  higher  fusing  point,  unless  it  is  held  in  one  place  for  a 
long  time. 

To  successfully  fill  a  thin  i)ure  gold  matrix  with  coin  gold  requires 
care,  but  a  little  careful  practice  with  the  blow-pipe  will  enable 
one  to  accompli-sh  it  with  very  little  danger  of  burning.  If  too 
much  air  is  used,  it  will  give  a  hotter  flame,  and  perhaps  l)urn  the 
matrix.     The  pure  gold,  being  of  a  higher  carat,  with  a  slightly 


184 


PROSTHESIS 


higher  fusing  point,  will  withstand  a  greater  heat  and  allow  the 
coin  gold  to  melt  and  fill  the  matrix,  provided  the  heat  is  con- 
centrated upon  the  coin  gold. 

The  cusp  matrix  can  also  be  filled  by  keeping  a  small  hot 
blue  flame  on  the  button  of  coin  gold  until  it  melts  and  fills  the 
cusp  (Fig.  261),  but  care  must  be  exercised  to  keep  it  on  the  coin 
gold  all  the  time,  because  if  it  should  be  moved  a  little  to  one  side, 


Fig.  263 

so  that  the  flame  strikes  the  pure  gold,  it  will  be  promptly  burned 
as  it  is  so  very  thin,  and  the  flame  so  very  hot.  After  it  has  been 
properly  filled,  it  is  cleansed  and  the  under  surface  of  the  cusp  is 
filed  perfectly  flat  (Fig.  262). 

In  order  to  file  this  surface  easily,  the  cusp  should  be  held 
firmly.  This  can  best  be  done  by  setting  it  in  the  end  of  a  soft 
pine  stick.  The  cusp  is  laid,  flat  side  down,  on  an  anvil,  the 
end  of  the  soft  pine  stick  resting  upon  it,  and  the  stick  struck  a 


CONSTRUCTIXG  A   CONTOURED  GOLD  CROWN 


185 


sharp  blow,  with  a  mallet  or  hammer,  thus  driving  the  cusp  into 
the  wood  (Fig.  263). 

Another  method  is  to  heat  the  cusp  red  hot  and  place  it  on  an 
end  of  the  stick,  cusp  down  and  let  it  burn  its  way  into  the  wood 
until  it  is  nearly  flush.  Either  method  will  hold  the  cusp  firmly, 
so  that  it  can  be  easily  filed. 

Uniting  the  Cusp  to  the  Band. — After  filing,  the  cusp  is  wired  to 
the  band  in  its  proper  position,  the  wire  being  brought  over  the  cusp 
and  across  the  gingival  end  of  the  band,  and  twisted  in  the  center 
so  as  to  draw  and  hold  the  cusp  in  contact  with  the  edge  of  the  band. 


Fig.  265 


Then  the  line  of  contact  between  the  band  and  the  cusj)  is  well 
fluxed. 

The  twisted  ends  of  the  wire  are  grasped  in  a  pair  of  pliers  and 
the  crown  held  over  the  tip  of  a  Bunsen  flame  (Fig.  204).  As  the 
cusp  b(;comes  thoroughly  heated  and  the  gold  almost  reaches  the 
fusing  j>(>iiit,  the  crown  is  lowered  slowly  toward  th(;  center  of 
the  flame  (Fig.  265).  By  watching  it  carefully  a  dark  line  appear- 
ing like  flowing  solder,  will  seem  to  flash  around  the  cusp  where 


186  PROSTHESIS 

it  joins  the  band.  This  is  the  metal  melting,  and  indicates  that 
the  cusp  and  the  band  are  perfectly  united. 

As  before  stated,  the  crown  should  be  held  to  the  tip  of  the  flame 
until  the  cusp  has  become  thoroughly  heated.  If  it  is  at  once 
lowered  into  the  flame,  the  cusp,  being  so  thick  and  heavy, 
becomes  heated  very  slowly,  and  the  flame  passing  up  around  its 
sides  would  melt  and  ruin  the  lighter  band  before  the  cusp  was 
hot  enough  to  be  sweated  to  it. 

It  should  be  remembered,  that  in  sweating,  the  parts  to  be 
united  should  be  brought  to  nearly  the  same  degree  of  heat,  other- 
wise one  part  will  melt  before  the  other,  and  there  will  be  no  union. 


CHAPTER  X. 
THE  MAKING  OF  THE  CROWxXS. 


RICHMOND  OR  PORCELAIN-FACED  CROWNS. 

In  making  a  banded  crown  for  any  of  the  teeth  in  the  anterior 
part  of  the  mouth,  the  stump  should  be  left  standing  from  one- 
thirty-second  to  one-sixteenth  of  an  inch  out  of  the  gum,  until 
after  the  root  has  been  trimmed  and  the  band  fitted. 

After  trimming,  the  measurement  of  the  root  is  taken  with  a  wire, 
straight  across,  at  right  angles  to  the  long  axis  of  the  root  (Fig.  266). 
It  should  not  follow  the  festoon  of  the  gum  line, 
as  that  would  carry  the  measuring  wire  lower  on 
the  buccal  and  lingual  sides  than  on  the  mesi«,l  and 
distal,  bringing  it  on  a  curve  so  that  when  the  wire 
was  straightened  out  it  would  be  larger  than  the  cir- 
cumference of  the  root. 

The  gokl  strip  is  cut,  to  measurement,  with  the 
ends  parallel  with  each  other  so  that  when  the  band 
is  made  the  sides  will  be  parallel.      One  end  is  beveled  and  the 
lap  made,  and  the  band  is  sweated  together  and  afterwards  shaped 
and  fitted  to  the  stump,  as  in  the  case  of  the  molar  crowns  already 
described. 


Fig.  266 


Fig.  207. — Kirk's  dentinictcr,  suilablo  lor  t:ikiiiK  flu;  moasuremcnt  of  roots. 

It  should  be  carried  well  under  the  gum,  especially  on  the  labial 
side,  being  festooned  carefully  to  follow  the  gum  line  (Fig.  2()8). 
After  the  band  has  been  fitted  it  is  removed  and  the  root  faced 
off,  cutting  well  beneath  the  gum  on  the  labial  side  so  that  the 
band  will  be  entirely  hidden.  This  ordinarily  woukl  be  carried 
about  one  thirty-second  of  an  inch  below  and  at  times  even  to  a 
greater  depth  if  the  conditions  are  such  to  allow  of  its  being  done. 

This  work  is  accomplished  with  the  root  facers  in  the  manner 


188 


THE  MAKING  OF   THE  CROWNS 


already  described,  after  which  the  band  is  replaced  on  the  stump 
and  forced  up  as  far  as  it  will  go.  It  is  then  scribed  around  on  the 
inside,  jBush  with  the  face  of  the  stump,  with  a  sharp  instrument. 
The  band  is  now  removed  and  trimmed  and  filed  to  this  line  with 


Fig.  268 


Fig.  269 


a  very  fine  flat  file.  The  cutting  and  filing  must  be  done  very 
carefully,  as  the  band,  being  narrow  and  frail,  is  easily  bent  out  of 
shape.  After  filing,  it  is  again  tried  on  the  root,  so  as  to  be  sure 
that  it  has  not  become  distorted,  before  sweating  on  the  floor 
(Figs.  270  and  271). 


Fig.  270 


Fig.  271 


It  is  not  necessary  that  the  band  be  wide  on  the  labial  side. 
In  fact  it  is  rarely  that  it  should  be  more  than  one-thirty-second  of 
an  inch  in  width  at  this  point.  It  is  only  necessary  that  it  extend 
over  far  enough  to  get  a  good  grip  on  the  root,  but  great  depth  is 


RICHMOND  OR  PORCELAIN-FACED  CROWNS 


189 


not  essential,  as  the  greatest  strength  of  the  band  is  at  the  point 
nearest  to  the  floor. 

The  band  being  properly  filed,  a  piece  of  coin  gold,  Xo.  30  gauge, 
is  prepared  about  one-sixteenth  of  an  inch  larger  than  the  band. 
This  is  made  perfectly  flat.  A  little  swaging  device  is  used  for  this 
purpose,  consisting  of  a  steel  anvil  with  a  flat,  smooth  face,  inserted 
in  one  end  of  a  brass  tube  and  having  a  steel  plunger  with  a  per- 
fectly flat  polished  face  which  fits  into  the  tube  (Fig.  271). 

The  metal  for  the  floor  is  annealed  and  then  placed  on  the  center 
of  the  anvil  at  the  bottom  of  the  tube.  The  steel  plunger  is  then 
inserted  into  the  tube  over  the  gold  and  tapped  with  a  hammer 
until  the  metal  is  perfectly  flat. 

The  gold  is  then  cleansed  in  acid.  The  band  is  now  placed  on 
this  piece  of  gold  so  that  it  extends  about  an  even  distance  from  the 
edges  all  around.  It  is  fluxed,  one  corner 
of  the  floor  grasped  in  a  pair  of  pliers  and 
held  in  the  Bunsen  flame  until  it  is  sweated. 
The  band  and  floor  being  of  about  the 
same  thickness,  it  should  be  held  near  the 
middle  of  the  flame,  so  that  the  flame  will 
spread  and  come  up  around  and  over  the 
cap,  heating  both  the  band  and  the  floor 
equally  (Fig.  272). 

As  the  piece  is  held  in  the  flame,  the 
edges  of  the  floor  will  begin  to  melt  and 
curl  up  slightly,  just  as  the  floor  and 
band  reach  the  fusing  point.  When  this 
is  seen    it  is    removed   from    the    flame. 

It  will  generally  be  found  that  at  the  corner  where  the  floor  was 
grasped  by  the  pliers,  the  band  and  floor  have  not  been  united, 
owing  to  the  pliers  drawing  the  heat  from  the  gold  at  this  point. 
The  floor  is  again  caught  by  the  opposite  corner  and  held  in  the 
flame  until  the  two  parts  are  thoroughly  united  all  around.  The 
surplus  metal  of  the  floor  is  now  trimmed  flush  with  the  side  of  the 
baiul.     It  is  then  ready  for  the  pin. 

Where  to  Drill  the  Hole  in  the  Floor  of  the  Cap  for  the  Pin. — There 
are  several  ways  of  locating  the  point  at  which  to  drill  the  hole 
for  the  pin  in  the  floor  of  the  cap.  Some  operators  use  wax  on  the 
under  side  of  the  cap  and  press  the  cap  on  the  root,  the  i)osition 
of  the  hole  is  thus  marked  on  the  wax.  Others,  place  in  the  root  a 
short  post  with  a  sharpened  end  projecting  just  above  the  face  of 


Fig.  272 


190 


THE  MAKING  OF   THE  CROWNS 


the  root,  so  that  when  the  cap  is  forced  in  place  it  will  make  a 
mark  over  the  opening.  But  such  methods  are  not  necessary  and 
take  up  valuable  time. 

In  the  six  anterior  teeth  the  canals  are  exactly  in  the  center  of 
the  root.  In  enlarging  the  canal  for  a  post  for  a  Richmond  crown, 
after  having  followed  the  canal,  the  reamer  is  partly  withdrawn  and 
the  canal  given  a  lingual  slope,  cutting  it  in  that  direction  about  the 
width  of  the  pin  lingually  from  the  original  line  of  the  enlarged 
canal  (Fig.  273).  In  making  the  hole  in  the  floor  of  the  cap,  first 
locate  the  center  of  the  floor  and  then  drill,  or  punch  the  hole  in  the 
floor  just  the  width  of  the  post  lingually  (Fig.  274),  and  then  by 
giving  the  post  a  slight  bend,  to  follow  the  canal,  it  will  pass 
through  the  floor,  far  enough  from  the  buccal  side  to  allow  of 
plenty  of  room  for  the  facing.  This  will  apply  to  any  of  the  six 
anterior    teeth.     When   making   a  porcelain   crown,   the  hole   is 


Fig.  273 


Fig.  274 


Fig.  275 


Fig.  276 


drilled  exactly  in  the  center  of  the  floor  and  we  know  of  a  cer- 
tainty that  the  post  will  be  in  its  proper  position. 

The  pin  for  a  first  bicuspid  crown,  should  always  be  placed  in  the 
lingual  root.  Unless  the  stump  has  been  broken  or  decayed  far 
below  the  gum  so  as  to  make  the  two  roots  very  short,  there  is  no 
necessity  for  using  more  than  a  single  pin.  The  force  exerted  on 
these  teeth  is  always  upward  and  outward,  there  being  practically 
no  stress  at  all  in  the  lingual  direction  (Fig.  275).  If  a  single  pin 
were  placed  in  the  buccal  canal,  the  force  being  outward  and  upward, 
it  would  tend  to  loosen  the  crown  from  the  lingual  side,  perhaps 
enough  so  that  the  edge  of  the  band  would  clear  the  root  at  this 
point,  with  the  result  that  the  crown  would  be  forced  outward, 
and  would  almost  certainly  fracture  the  buccal  side  of  the  root 
(Fig.  276). 

If  the  post  be  placed  in  the  lingual  root,  the  cap  is  bound  down 


RICHMOND  OR  PORCELAIN-FACED  CROWNS 


191 


tightly  at  that  point,  and  there  is  but  Httle  risk  of  its  being  forced 
outward,  or  being  loosened  from  the  buccal  side,  as  the  force  of 
mastication  will  keep  it  pressed  tightly  against  that  face  of  the  root 
(Fig.  277). 


Fig.  277 


Fig.  278 


Fig.  279 


Fig.  280 


In  order  to  locate  the  opening  in  which  to  place  the  pin  in  these 
roots,  follow  out  the  lingual  curve  to  a  complete  circle  on  the  floor 
of  the  cap,  and  drill  the  hole  exactly  in  the  center  of  this  circle. 
The  pin  will  then  enter  the  canal  freely  (Fig.  278). 

The  second  bicuspid,  has  but  a  single  root,  but  this  is  broad  and 
flat,  and  there  is  more  leeway  than  in  the  first  bicuspid.  In  this 
case  drill  the  hole  a  little  lingually  from  the  center,  having  enlarged 
the  canal  along  this  same  line.  It  will  also  give  more  room  in 
which  to  place  the  pin,  as  the  root  is  somewhat  constricted  in 
the  center  (Fig.  279). 

In  grinding  the  facings  for  the  Richmond  crowns,  it  is  better 
that  they  should  be  ground  flat  to  fit  the  floor  of  the  cap  (Fig.  280), 
especially  in  the  six  anterior  teeth  where  there  is  a  likelihood  of 
the  gold  being  seen  from  the  front  if  the  facings  are  beveled  so 


Fia.  281 


Fig.  282 


Fig.  283 


as  to  just  come  in  contact  with  the  Hof)r  only  at  the  labial  side 
(Fig.  281  J.     With  the  bicuspids  there  is  not  the  same  likelihood  of 


192  THE  MAKING  OF  THE  CROWNS 

the  gold  being  visible  between  the  necks  of  the  teeth,  so  there  is  no 
objection  to  beveling  the  lower  part  of  the  facing,  if  it  is  desired. 

The  hole  in  the  floor  having  been  located  and  drilled,  the  cap  is 
placed  on  the  root  and  the  pin  put  in  position,  carrying  it  as  far 
down  the  canal  as  possible,  waxed  in  place,  removed,  invested  and 
soldered  (Fig.  282).  These  pins  are  preferably  made  of  round 
platinized  gold  clasp  wire,  and  should  be  of  about  No.  14  to  16 
gauge,  the  size  of  the  pin  depending  on  the  tooth  which  is  to  be 
crowned. 

Backing  and  Soldering. — The  backings  for  these  teeth  are  pre- 
ferably made  of  soft  platinum  about  three  or  four  one-thousandths 
of  an  inch  in  thickness.  Crown  metal  plate  which  has  one  surface 
of  gold  and  the  other  of  platinum  may  also  be  used.  If  it  is  desired 
to  lighten  the  shade  of  the  tooth,  the  gold  side  is  placed  next  to 
the  facing.  The  backings  should  fit  the  facing  closely  and  extend 
from  the  lower  edge  of  the  lingual  side  of  the  facing  to  about  one- 
sixteenth  of  an  inch  beyond  the  incisal  edge,  as  in  Fig.  283.  The 
pins  are  flattened  and  then  bent  upward  toward  the  incisal  edge 
and  against  the  backing,  thus  holding  it  close  to  the  facing.  The 
pin  roughing  and  bending  pliers  are  used  for  this  purpose  and  are 
shown  in  Fig.  284. 

Fig.  285  shows  a  small  wax  spatula  especially  adapted  for  light 
work  of  this  kind. 

The  facing  is  waxed  in  position  on  the  cap  with  sticky  wax. 
After  it  has  chilled,  it  will  be  found  that  the  contraction  of  the 
wax  on  cooling  has  tilted  the  facing  slightly  so  that  it  rides  on 
the  cap  on  the  lingual  side  of  the  ground  portion  of  the  facing 
raising  its  labial  side  clear  from  the  floor  of  the  cap  (Fig.  286). 
If  it  were  soldered  without  remedying  this  defect,  the  facing  would 
be  still  further  drawn  from  the  floor  on  the  labial  side,  due  to  the 
contraction  of  the  solder,  leaving  a  V-shaped  space  between  the 
facing  and  the  floor  of  the  cap. 

To  overcome  this  difficulty,  after  the  facing  has  been  waxed, 
it  should  be  pressed  outward  at  the  incisal  edge  until  the  labial 
side  presses  on  the  floor  of  the  cap,  and  the  lingual  side  is  just 
clear  of  it,  so  that  if  it  is  held  up  to  the  light,  it  can  be  seen  that 
it  is  not  in  actual  contact  at  that  point  (Fig.  287).  If  this  has 
been  done,  when  the  crown  is  soldered,  the  contraction  of  the 
metal  will  draw  the  facing  close  to  the  floor  on  the  lingual  side, 
without  disturbing  its  contact  on  the  labial  side,  thus  making  a 
perfect  joint. 


RICHMOND  OR  PORCELAIN-FACED  CROWNS  193 


Fig.  284 


13 


194 


THE  MAKING  OF   THE  CROWNS 


The  investment  should  be  only  large  enough  to  hold  the  parts 
in  position  (Fig.  288).  A  small  amount  of  the  investment  is  placed 
on  the  slab  and  smoothed,  as  in  soldering  a  porcelain  crown.  The 
inside  of  the  cap  is  filled  with  investment  and  laid  face  down  on 


Fig.  285 

the  investment  which  has  been  placed  on  the  slab  and  settled  in 
place  until  the  lingual  side  of  the  facing  is  exactly  flush.  The  pin 
is  covered  with  investment  and  the  extending  backing  on  the 
incisal  edge  is  also  covered,  bringing  it  flush  with  the  lingual  side 
of  the  facing,  as  in  Fig.  289. 


Fig.  286 


Fig.  287 


After  the  investment  has  hardened,  it  is  warmed  slightly  and  the 
wax  removed,  after  which  it  is  heated  thoroughly,  and  soldered. 
No  more  solder  should  be  used  than  is  necessary  to  restore  the 
normal  contour  of  the  tooth,  but  the  incisal  edge  should  be  covered 
thickly.  After  it  has  cooled,  it  is  removed  from  the  investment, 
cleansed  in  acid  and  finished. 


Fig.  288 


Fig.  289 


The  gold  at  the  incisal  edge  should  be  left  as  thick  as  the  bite 
will  permit,  in  order  to  protect  the  facing,  and  it  should  be  ground 
so  as  to  leave  it  a  little  higher  on  the  lingual  side,  but  not  enough 
so  that  it  can  be  seen  (Fig.  290). 


PORCELAIN  CROWNS  {DOWNEY   CROWNS) 


195 


The  normal  shape  of  the  tooth  should  be  restored  as  nearly  as 
possible.  The  lingual  surface  of  the  incisors  should  be  made  con- 
cave from  the  incisal  edge  for  about  half  the  length  of  the  crown 
(Fig.  291),  and  not  convex  as  is  so  frequently  done  (Fig.  292). 

The  Richmond  or  pin  crowns,  and  shell  crowns  are  the  principal 
attachments  used  in  fixed  bridge-work. 


Fig.  290 


Fig.  291 


Fig.  292 


PORCELAIN  CROWNS   (DOWNEY  CROWNS). 

In  making  a  so-called  Downey  crown  for  any  of  the  six  anterior 
teeth,  where  a  facing  is  used,  and  the  lingual  side  built  up  with 
porcelain,  the  root  is  given  a  double  slope  in  the  manner  already 
described,  cutting  well  beneath  the  gum  labially  and  carrying  it 
just  about  to  the  gum  on  the  palatal  side  (Fig.  293). 

The  cap  is  made  of  iridio-platinum  plate.  No.  32  gauge,  and  in 
the  same  manner  as  the  cap  of  a  Richmond  crown,  with  the  ex- 


Fig.  29.3 


Fh;.  294 


Fig.  295 


ception  of  its  being  soldered  with  pure  gold  and  lia\iug  a  double 
slope  (Fig.  294;. 

The  pin  is  placed  exactly  in  tiic  center  of  tlie  cap,  and  the  facing 
ground  so  that  the  gingival  end  touclies  the  Hoor  lightly  at  the  labial 
side  only  fFig.  29.')).  'i'his  will  allow  of  the  porcelain  body  being 
worked  inidcr  the  faring  n'lorc  readilx'  than  if  the  facing  had  a  broad 
C()ntact  with  the  floor.  The  fiiciiig  iii;iy  be  grooved  out  between 
the  pins  to  permit  of  l\\v.  post  setting  well   into  the  facing  (i^'ig. 


196 


THE  MAKING  OF  THE  CROWNS 


296),  allowing  plenty  of  room  on  the  palatal  side  for  the  porcelain 
body.  The  two  pins  may  be  notched  slightly  with  the  edge  of  a 
small  half-round  file  (Fig.  297)  toward  the  incisal  end  to  allow  of 
their  being  bent  flat  against  the  facing,  and  bring  them  in  contact 
with  the  sides  of  the  post  (Fig.  295).  They  should  not  be  bent 
out  and  around  the  post,  as  this  would  frequently  carry  them  so 
far  lingually  as  to  show  through  the  porcelain,  and  consequently 
weakening  the  crowns. 


Fig.  296 


Fig.  297 


After  the  pins  are  bent  in  contact  with  the  sides  of  the  post, 
they  are  waxed  firmly  with  hard  sticky  wax.  A  small  amount  of 
wax  should  be  flowed  around  the  labial  edge  of  the  band  between 
it  and  the  facing  to  prevent  any  of  the  investment  material  from 
working  in  between  the  facing  of  the  cap. 

In  investing  this,  for  soldering  the  pins  to  the  post,  a  small  amount 
of  investment  is  placed  on  the  slab  and  smoothed  off  perfectly 
flat,   leaving  it  from  about  three-eighths  to  one-half  an  inch  in 


Fig.  298 


Fig.  299 


thickness.  The  crown  is  then  laid  face  down  on  the  investment 
and  pressed  lightly  until  it  is  imbedded  even,  or  flush,  with  the 
lingual  side  of  the  facing.  A  little  of  the  investment  is  then  placed 
over  the  end  of  the  pin  to  hold  it  in  position  (Fig.  298). 

No  investment  should  be  placed  inside  of  the  cap.  This  should 
be  kept  perfectly  clear,  the  bulk  of  the  pin  and  the  cap  being  exposed 
to  the  flame.  If  the  cap  is  filled  with  investment  material,  and  the 
post  and  cap  thoroughly  covered,  as  in  the  illustration  (Fig.  299), 


JACKET  CROWNS  197 

it  will  require  a  greater  length  of  time,  and  much  more  heat  to  unite 
the  pins  to  the  post,  as  there  would  then  be  such  a  large  mass 
of  investment  to  heat  up.  The  investment  taking  the  heat  from  the 
post,  would  make  it  very  difficult  to  get  it  hot  enough  to  solder  the 
pins  of  the  facing  to  it  with  pure  gold.  On  the  other  hand,  if  the 
cap  and  the  larger  part  of  the  post  is  left  exposed,  as  soon  as  the 
investment  is  heated  up  to  a  red  heat,  by  throwing  the  flame  on 
the  metal  parts,  the  pure  gold  will  quickly  flow  in.  between  the 
pins  and  the  post. 

The  flame  of  the  blowpipe  should  never  be  thrown  on  the  metal 
parts  until  after  the  investment  and  facing  are  thoroughly  heated 
to  a  bright  red  heat,  otherwise  the  facing  will  be  broken,  owing  to 
the  sudden  expansion  of  the  platinum  pins.  After  it  has  been  sol- 
dered, it  is  cleansed  in  acid  and  is  ready  for  the  application  of  the 
porcelain  body. 

HALF   CAPS    OR  WINDOW   CROWNS. 

The  half  cap,  or  window  crown,  was  at  one  time  used  quite 
extensively  as  an  anchorage  for  bridges.  It  was  very  unsightly 
and  was  a  very  poor  attachment  to  say  the  least,  and  while  at 
the  present  time  there  are  some  who  still  use  it,  it  is  becoming 
obsolete,  so  that  it  would  be  a  waste  of  time  to  go  into  a  description 
of  its  construction. 

JACKET  CROWNS. 

The  jacket  crowns  are  designed  to  be  used  where  it  is  desirable 
to  avoid  devitalizing  a  tooth.  They  are  indicated  when  it  is 
necessary  to  crown  peg-shaped  laterals  or  unde- 
veloped teeth  of  a  similar  character,  where  the 
crowns  are  very  small,  or  where  the  crowns  of 
teeth  are  much  decayed,  and  the  pulps  have 
receded  (Fig.  300).  ^'°-  ^^^ 

The  method  of  making  these  crowns  varies  according  to  conditions 
to  be  met,  and  the  materials  used  in  their  construction. 

VVhere  the  crowns  are  needed  for  much  decayed  anterior  teeth,  the 
labial  face  of  the  tooth  is  ground  awa}-  as  much  as  possible  without 
endangering  the  life  of  the  pulp,  cutting  well  under  the  gum,  as  in 
Fig.  301.  The  enamel  is  also  removed  from  the  sides  and  palatal 
portion  so  that  the  band  will  hug  the  root  tightly  under  the  gum. 
The  band  is  then  made  and  fitted  to  the  stump  and  cut  out  on  the 
labial  side  flush  with  the  tooth  (Fig.  302).    The  palatal  side  of  the 


198 


THE  MAKING  OF   THE  CROWNS 


band  is  pressed  in  close  to  the  stump  and  the  mesial  and  distal 
sides  of  the  band  spread  out  nearly  to  the  width  of  the  facing  which 
is  to  be  used,  and  a  floor  of  coin  gold  sweated  or  soldered  to  it 
(Fig.  303).  A  thin  facing  is  then  ground  so  as  to  leave  a  little  space 
between  it  and  the  cap,  touching  the  latter  only  at  the  gingival  end 


) 


Fig.  302 


Fig.  301 


Fig.  303 


(Fig.  304) .  The  facing  is  now  backed  with  thin  platinum  or  crown 
metal,  which  is  allowed  to  extend  about  one-sixteenth  of  an  inch 
beyond  the  incisal  edge.  It  is  then  waxed  to  the  cap,  invested 
and  soldered,  flowing  the  solder  between  the  facing  and  the  cap 
and  if  necessary  over  the  palatal  portion  of  the  band  (Fig.  304). 

Another  method  of  making  the  jacket  crown 

.         is  to  carry  the  band  to  the  full  height  of  the 

/\  /]        tooth,  to  contour  it,  and  cut  it  out  on  the  face 

j|M  I/*        to  the  depth  of  the  facing.    The  facing  is  then 

^^  ^  ground  to  fit  the   edge   of   the  cap   so  formed 

Fig.  304     Fig.  305     and  a  backing  of  coin  gold  fitted  carefully  to  it  (Fig. 

305) .    This  backing  with  the  facing  in  position, 

is  then  adjusted  to  the  cap,  waxed,  the  facing  removed  and  the 

backing  sweated,  or  soldered  to  the  cap  with  22  carat  solder  (Fig. 

306) .    The  facing  is  then  put  in  place,  the  pins  waxed  on  the  inside 

of  the  cap,  and  the  crown  invested.     The  crown  is  invested  face 

down  and  covered  but  lightly,  leaving  the  opening  fully  exposed, 


Fig.  306 


Fig.  307 


Fig.  308 


as  in  Fig.  307.  It  is  thoroughly  dried  out  and  flux  placed  on  and 
around  the  pins.  A  piece  of  18  or  20  carat  solder  is  then  placed 
over  the  pins,  the  whole  brought  to  a  brigth-red  heat,  and  with 
the  fine  blue  point  of  the  blow-pipe  flame  thrown  on  the  inside, 
the  solder  is  melted,  uniting  the  facing  to  the  cap.  Fig.  308  shows 
the  completed  crown. 


CASTING  PROCESS  IN  CROWN   WORK  199 

In  making  a  porcelain-faced  crown  for  a  bicuspid  having  a  vital 
pulp,  the  tooth  is  prepared  in  the  same  way  as  for  an  anterior 
tooth,  cutting  it  well  out  on  the  buccal  side,  and  grinding  away 
the  inner  cusp  (Fig.  309) .  The  band  is  then  made  as  for  a  full  gold 
crown,  and  cut  even  with  the  cusp  at  the  top  and  enough  on  the 
buccal  side  to  allow  for  the  facing  (Fig.  310).  The  facing  is  then 
ground  to  fit  the  edges  of  the  cap  (Fig.  311),  and  a  backing  of 
coin  gold  fitted  to  it.  The  backing  being  fitted  to  the  facing, 
it  is  placed  in  position  on  the  cap  and  waxed  and  soldered  with 
22-carat  solder.  The  backing  is  then  cut  oft'  even  with  the  rest 
of  the  band  and  filed  flat  (Fig.  312).  The  tip  of 
the  facing  is  then  ground  on  a  bevel  with  an  angle 
of  about  45°,  the  lower  edge  of  the  bevel  being  on 
a  line  with  the  top  of  the  cap  (Fig.  313). 

A  cusp  is  then  selected,  the  under  surface  filed 
flat  and  the  buccal  side  beveled  to  meet  the  bevel 
of  the  facing  (Fig.  314).    The  cusp  is  then  wired  to  Fig.  309 

the  cap  and  soldered  with  22-carat  solder,  the  facing 
having  first  been  removed.  The  cap  is  then  cleansed  in  acid  and 
the  facing  replaced  in  position  and  waxed.  It  is  then  invested  and 
soldered  from  the  inside  as  already  described  in  Fig.  307.  The 
jacket  crowns  described  can  be  used  as  abutments  in  fixed  bridge 
work. 

Where  it  is  desired  that  the  crown  should  be  of  all  porcelain, 
the  cap  should  be  made  of  soft  platinum,  No,  32  gauge,  and 
fitted  carefully  to  the  stump  all  around.    The  facing  is  then  ground 


^ 


Fici.  310         Fig.  311       Fig.  312        Fig.  313        Fig.  314 

in  place  and  attached  to  the  caps  by  means  of  the  pins  soldered  to 
it  with  a  very  minute  quantity  of  pure  gold,  after  which  the  crown 
is  completed  by  building  up  with  porcelain. 

THE  CASTING  PROCESS  AND  ITS  AVAILABILITY  IN  CROWN 

WORK. 

The  introduction  of  the  casting  jiroccss  opened  up  a  large  field 
in  this  braric-h  of  prosthesis,  but  it  must  be  employed  with  a  full 


200  THE  MAKING  OF  THE  CROWNS 

recognition  of  its  limitations.  Cast  gold  is  not  as  strong  as  rolled 
gold,  and  a  bridge  of  cast  gold  is  not  as  strong  as  one  built  up  and 
soldered.  The  shrinkage  of  the  metal  in  cooling  must  also  be  taken 
into  account  or  failure  on  that  score  is  sure  to  result. 

The  metal  used  for  this  work  should  be  of  a  high  carat,  and  of 
as  great  tensile  strength  and  rigidity  as  possible.  It  should  not  be 
overheated.  Coin  gold  appears  to  be  well  adapted  for  this  purpose 
as  it  possesses  the  qualities  above  mentioned  and  gives  a  good 
sharp  casting. 

All  Porcelain  Crown  with  Cast  Base. — This,  being  one  of  the  simplest 
and  easiest  crowns  to  make,  will  be  first  considered.  The  root 
for  a  crown  of  this  character  requires  little  preparation,  as  com- 
pared with  one  for  a  Richmond  or  other  banded  crown.  The  face 
of  the  root  may  be  irregular  from  decay  or  fracture,  or  it  may  have 
been  ground  down  to  meet  the  requirements  of  the  case.  In  any 
event,  it  should  be  cut  well  beneath  the  gum  line  on  the  labial  side, 
and  on  the  lingual  side  enough  to  suit  the  requirements  of  occlu- 
sion. The  lingual  side  should,  if  it  is  possible,  be  beveled  so  that 
the  base  will  overlap,  thus  giving  additional  support  to  the  crown, 
and  at  the  same  time,  serving  to  strengthen  the  root  and  overcome 
the  liability  of  fracture  (Fig.  315). 

The  crowns  used  for  this  purpose  may  be  any  of  the  numerous 
varieties  which  are  made  by  the  different  manufacturers,  even  to 
the  diatoric  teeth  which  are  made  for  vulcanite  work.  The  crown 
selected  is  ground  to  conform  to  the  size  and  shape  of  the  root, 
and  to  touch  it  only  at  the  labial  side,  leaving  plenty  of  room  between 
the  face  of  the  root  and  the  crown  to  allow  of  a  heavy  base,  as  in 
Fig.  316. 

The  post,  or  pin,  which  is  preferably  made  of  iridio-platinum 
or  platinized  gold  wire,  is  then  adjusted,  and  should  be  of  sufficient 
length  to  go  nearly  or  quite  to  the  bottom  of  the  hole  in  the  base 
of  the  crown  and  into  the  root  to  a  depth  at  least  equal  to  the  length 
of  the  crown  (Fig.  316).  It  is  well  to  first  flow  a  little  sticky  wax 
around  the  post,  between  the  base  of  the  crown  and  the  face  of  the 
root,  at  point  a  in  Fig.  316,  as  the  wax,  of  which  the  base  is  to  be 
made,  will  adhere  to  the  post  better  than  it  would  otherwise. 

The  base  of  the  crown  should  be  moist  or  be  lightly  oiled  or 
coated  very  thinly  with  cocoa-butter  to  prevent  the  wax  from 
adhering  to  it,  and  the  base  wax,  which  should  be  a  little  softer 
and  tougher  than  the  ordinary  inlay  wax,  is  softened  and  pressed 
around  the  pin  at  the  base  of  the  crown,  which  is  forced  on  the 


CASTING  PROCESS   IN  CROWN   WORK 


201 


root  and  carefully  adjusted  in  position.  After  the  wax  has  been 
chilled,  the  surplus  should  be  carefully  trimmed,  until  it  is  per- 
fectly smooth  and  flush  with  the  sides  of  the  crown  and  root 
(Fig.  317).  The  crown,  together  with  the  pin,  is  then  removed 
from  the  root  and  the  sprue  wire  attached,  or  it  may  be  attached 
in  the  mouth  as  in  Fig.  317,  by  heating  it  just  sufficient  to  imbed 
it  slightly  in  the  wax.     It  may  be  more  firmly  fixed   by  flowing 


Fig.  315 


Fig.  31G 


Fig.  317 


a  very  small  amount  of  wax  around  it  at  the  point  of  entrance, 
after  which  the  crown  has  been  removed. 

The  sprue  wire  is  now  placed  in  the  base  of  the  flask  (Fig.  318) 
and  the  crown  base  is  invested  in  the  same  manner  as  an  inlay, 
painting  the  investment  on  very  carefully  so  that  there  may  be 
no  air  bubbles,  which  would  be  reproduced  in  gold  in  the  casting 
and  interfere  with  the  fit  of  the  base.    After  casting,  it  is  cleansed 


Fig.  318 


and  polished  and  adjusted  to  the  crown  and  root.  The  base  is 
first  cemented  to  the  crown  and  after  the  cement  has  thoroughly 
hardened,  it  is  cemented  in  the  mouth. 

This  makes  a  satisfactory  crown  when  used  singly,  but  it  is  not 
suitable  for  a  bridge,  as  all  bridge  abutments  should  be  banded. 

Banded  Crowns.^ — The  caps  for  these  crowns  can  be  made  in  the 
same  nianncr  as  for  a  Richmond  crown,  being  carried  well  beneath 


202  THE  MAKING  OF  THE  CROWNS 

the  gum  labially.  The  impression  is  taken  and  the  model  prepared 
in  the  usual  way. 

The  crown  is  ground  in  the  manner  already  described  in  treat- 
ing of  a  crown  with  a  cast  base,  being  beveled  lingually  and  on 
the  mesial  and  distal  sides  about  half  or  two-thirds  of  the  way  to 
the  labial  face  (Fig.  319).  This  allows  a  sort  of  a  socket  for  the 
crown  to  set  in,  and,  at  the  same  time,  insures  the  correct  position 
of  the  crown  on  the  base. 

The  base  of  the  crown  is  lubricated,  so  that  the  wax  will  not 
stick  to  it,  and  the  wax  flowed  in  between  the  crown  and  the  cap, 
until  it  is  well  filled,  after  which  it  is  carved  flush  with  the  crown 
and  the  band  and  the  sprue  wire  attached,  as  in  Fig.  320.  The 
crown  is  now  removed,  leaving  a  wax  base  attached,  as  in  Fig.  321. 
It  is  then  set  in  the  flask  base  and  invested  and  cast  in  the  usual 
manner.     The  base  should  be  polished  with  the  crown  in  position, 


Fig.  319  Fig.  320  Fig.  321 

after  which  the  crown  is  cemented  to  the  base  and  kept  under 
pressure  until  the  cement  has  hardened.  It  will  then  be  ready 
for  the  mouth. 

This  method  of  procedure  may  be  followed  in  making  any  crown 
of  this  type  from  molars  to  incisors. 

Casting  Base  for  Crown  with  Porcelain  Facings. — In  crowns  of 
the  Richmond  type,  where  a  porcelain  facing  is  used,  the  cap  and 
pin  are  made  and  fitted  to  the  root,  and  the  facing  ground  to  place 
sloping  it  slightly  more  than  the  floor,  so  as  to  allow  the  wax  to 
flow  under  the  facing  (Fig.  322).  If  there  has  been  much  recession 
of  the  gum,  so  that  the  band  has  to  be  sloped  greatly  labially  (Fig. 
323),  it  is  well  to  grind  a  step  in  the  bottom  of  the  facing,  in  order 
that  there  may  be  a  good  base  for  it  to  rest  on,  thereby  rendering 
it  less  hable  to  be  forced  down  the  incline  and  fractured  (Figs.  323 
and  324).  The  facing  should  then  be  lubricated  on  the  lingual 
side,  and  held  in  place  with  a  little  sticky  wax  on  the  labial  side, 


CASTING  PROCESS  IN  CROWN  WORK 


203 


or  a  light  wall  of  plaster  or  modeling  composition.     The  lingual 
side  should  be  built  up  with  hard  inlay  wax  and  carefully  carved 
and  smoothed  (P'ig.  325).    It  should  be  remembered  that  the  more 
carefully  the  crown  is  finished  in  the  wax,  the  easier  it 
will  be  to  finish  the  completed  crown. 

The  sprue  wire  is  attached,  as  shown  in  Fig.  325  the 
facing  carefully  removed  and  small  pins  of  graphite 
inserted  in  the  holes  left  by  the  tooth-pins,  leaving 
them  long  so  as  to  be  gripped  in  the  investment  (Fig. 
326). 

Another   method   is  to  enlarge  the   pin-holes   in    the 
wax  after  removing  the  facings  and   dovetail   them  on 
the  inside,  as  in  Figs.  327  and  328.     This  can  be  readily 
done  with  a  small  coarse   bur.      It  is  then  invested,  care  being 
taken  to  fill  with  the  investment  if  the  pin-holes  have  been  enlarged. 


Fig.  322 


Fig.  323 


Fig.  324 


Fig.  325 


1^ 


Fig.  326 


If  graphite  pins  have  been  used,  after  the  casting  has  been  made, 
they  are  removed,  the  sides  of  the  holes  roughened,  and  the  piece 
cleansed  and  polished.     The  tooth-pins  are  then  lightly  threaded 


Fig.  327 


Fig.  32« 


or  roughened  and  the  facing  cemented  in  j)lace.  If  the  holes 
were  enlarged  and  dovetailed,  the  pins  may  be  flattened  a  little 
and  then  bent  at  right  angles,  as  shown  in  Fig.  329,  and  cemented 
in  place. 


204  THE  MAKING  OF   THE  CROWNS 

Casting  Directly  on  the  Facings. J-In  making  a  single  crown  or  a 
small  bridge,  where  it  is  intended  to  cast  directly  against  the 
facings,  great  care  should  be  taken  that  the  wax  does  not  overlap 
the  porcelain  at  any  point.  This  is  of  the  utmost  importance, 
for  should  the  wax  be  extended  so  as  to  grip  the  facings  when  the 
casting  is  made,  the  contraction  of  the  metal  on  cooling  will  be 
certain  to  crush  them.  The  wax  should  be  carefully  trimmed  to 
the  edges  of  the  porcelain,  and  it  is  a  good  plan  to  clean  them  well 
by  rubbing  the  edges  with  a  piece  of  tape  or  cloth  before  investing. 

Drying  out  and  Heating  up  the  Flask. — The  flask  should  be  dried 
out  carefully  and  then  brought  to  a  very  high  heat  throughout  so 
that  the  facing  will  be  red  hot  when  the  gold  comes  in  contact  with 
it.  If  the  facing  is  cold,  or  but  slightly  heated,  when  the  casting 
takes  place,  the  rapid  expansion  of  the  platinum  pins,  taking  the 
heat  so  much  more  quickly  than  does  the  porcelain,  will  fracture 
the  facing.  After  casting,  the  flask  should  be  allowed  to  become 
cold  before  opening,  after  which  the  piece  is  cleansed  and  is  ready 
for  finishing. 

The  crown,  or  the  bridge,  which  has  been  made  in  this  way  will 
be  satisfactory,  providing  there  is  little  or  no  strain  on  the  facings, 
but  otherwise  the  method  is  decidedly  objectionable. 

In  a  facing  which  is  reheated,  in  soldering  or  otherwise,  the 
strength  of  the  porcelain  is  diminished,  and  especially  is  this  the 
case  if  a  mass  of  gold  is  forced  upon  it  in  a  molten  state.  The 
piece  may  come  out  with  the  facings  seemingly  intact,  but  they 
have  been  weakened  and  in  the  majority  of  cases,  if  examined  under 
a  microscope,  will  show  innumerable  fine  checks  running  all  through 
them.  If  it  is  possible  to  avoid  it,  it  is  far  better  not  to  subject 
the  facings  to  this  refiring,  as  they  are  thereby  rendered  much 
less  serviceable  than  they  otherwise  would  be. 


CHAPTER  XI. 
BRIDGE-WORK. 

A  DENTAL  bridge  consists  of  a  continuous  masticating  surface, 
or  of  a  succession  of  crowns  or  dummies  having  incisal  edges.  As 
fts  name  implies,  it  is  a  bridge  proper,  depending  for  its  retention 
and  support  upon  the  natural  teeth  or  roots  in  the  mouth,  which 
serve  as  abutments.  The  success  and  the  permanence  of  the  device, 
in  this,  as  in  the  case  of  any  other  form  of  a  bridge,  depends 
entirely  upon  the  number,  position  and  condition  of  the  abutments. 

The  primary  object  of  bridge-work  has  been,  and  is,  to  do  away 
with  the  inconveniences  associated  with  a  plate,  and  to  give  patients 
an  appliance  which  through  its  firmness  and  immobility  will  enable 
them  to  perform  the  masticatory  function  more  perfectly  than  can 
possibly  be  done  with  a  plate. 

The  natural  teeth  or  roots  supporting  a  bridge  are  called  the 
abutments,  and  the  intervening  portions  are  known  as  the  body  of 
the  bridge.  The  body  of  the  bridge  is  made  up  of  one  or  more 
pieces  representing  the  different  teeth  and  these  are  known  as 
dummies. 

The  idea  of  bridge-work  is  not  new.  We  fine  many  traces,  even 
among  the  ancients,  of  attempts  to  restore  lost  teeth.  These  early 
efforts  were  confined  almost  exclusively  to  fastening  together  with 
wire  the  crowns  of  natural  teeth,  and  these  in  turn  were  bound  to 
the  remaining  teeth  in  the  mouth  by  wires.  These  restorations 
were  entirely  for  esthetic  purposes,  and  were  of  no  practical  value 
to  the  wearer  for  mastication. 

Modern  bridge-work  is  of  comparatively  recent  date,  and  it  is 
only  within  the  past  thirty  or  thirty-five  years  that  it  has  been 
put  to  really  practical  use,  and  today  it  is  recognized  as  being  an 
important  specialty  of  the  dental  profession.  There  is  no  form  of 
denture  made  which  so  nearly  approaches  nature  in  the  restoration 
of  the  normal  function  of  the  lost  organs. 

CLASSIFICATION    OF   BRIDGES. 

Dental  bridges  arc  divided  into  two  primary  classes,  fixed  and 
removable. 


206  BRIDGE-WORK 

Fixed  bridges  are  those  which  are  attached  to  the  abutments  so 
that  it  is  impossible  for  the  patient  to  remove  them,  or  even  the 
dentist,  without  more  or  less  mutilation  of  the  abutment  crowns. 

Removable  bridges  are  those  which  can  be  removed  from  the 
mouth  by  the  patient  for  cleansing  of  other  purposes,  without 
interfering  with  or  disturbing  the  stability  or  integrity  of  the 
appliance. 

The  insertion  of  dental  bridge-work  requires  the  mutilation  of 
the  teeth,  serving  as  abutments,  to  a  greater  or  less  extent,  and  in 
nearly  every  case  the  pulp  must  be  sacrificed.  This  was  at  first 
considered  as  one  of  the  great  objections  to  bridge- work,  but  it 
was  simply  a  case  of  sacrificing  one  for  the  good  of  many.  If  the 
work  was  properly  done,  it  was  found  that  this  sacrifice  was  justified 
in  the  increased  comfort  and  improved  health  of  the  patient. 

The  value  of  bridge-work  is  unquestionable.  This  value  depends 
entirely  upon  the  manner  in  which  the  work  is  done,  and  where 
it  is  used  and  not  abused,  there  is  nothing  that  can  take  its  place. 

Bridge-work  is  not  universal  in  its  application,  and  is  not  intended 
to  do  away  with  other  forms  of  denture,  but  it  is  unquestionable 
that  in  a  large  number  of  cases  where  partial  plates  are  being  placed 
in  the  mouth,  that  they  are  in  reality  an  injury,  rather  than  a 
benefit  of  the  patient,  and  bridge-work  is  positively  indicated  and 
would  render  far  greater  service  than  is  possible  with  the  dentures, 
which  are  given  them. 

REQUISITES    OF    A   DENTAL   BRIDGE. 

The  first  requisite  of  a  dental  bridge  is  that  it  should  restore 
as  nearly  as  possible  the  lost  functions  and  appearance  of  the 
teeth  which  have  been  lost.  Esthetic  conditions  are  too  frequently 
lost  sight  of  in  this  work,  but  they  are  as  important  in  this  as  in 
any  prosthetic  operation,  and  as  much  attention  should  be  paid 
to  esthetic  effect  as  can  be  safely  done  without  sacrificing  the 
utility  of  the  piece. 

The  crowns  or  facings  which  are  to  be  used  should  be  carefully 
selected,  with  due  regard  to  their  proper  sizes,  shapes,  texture  and 
colors.  The  occlusal  surfaces  should  be  made  so  that  they  shall 
effectively  perform  the  work  of  mastication,  and  at  the  same  time 
with  no  undue  strain  on  the  abutments. 

Every  portion  of  the  bridge  should  be  made  with  the  idea  of 
accessibility  to  the  bristles  of  the  toothbrush  in  cleansing,  so  that 


THE  PREPARATION  OF  ABUTMENTS 


207 


it  may  be  kept  as  free  as  possible  from  foodstuffs  and  other  debris. 
Spaces  between  the  facings  themselves,  or  between  the  facings  and 
the  abutments  in  bridges  restoring  teeth  in  the  posterior  part  of 
the  mouth  should  be  partially  filled  with  gold  so  as  to  offer  as  little 
lodgment  for  foreign  substances  as  possible.  Unnecessary  exposure 
of  gold  is  always  to  be  avoided,  and  never  in  any  bridge,  placed 
anterior  to  the  bicuspids,  should  gold  be  shown. 

THE  PREPARATION  OF  ABUTMENTS. 

The  first  and  most  important  consideration  in  preparing  for  the 
insertion  of  a  bridge  is  the  condition  of  the  abutments.  The  direc- 
tions given  in  Chapters  IV-VI  on  the  treatment  and  the  preparation 


Fig.  330 


Fig.  331 


of  the  roots  and  the  perfect  adaptation  of  the  bands  to  the  stump 
or  roots  will  apply  with  far  greater  force  when  these  roots  are  to 
serve  as  abutments  for  a  bridge. 

Paralleling  the  Abutments. — Regarding  the  mutual  relation  of  the 
individual  abutments,  they  must  be  made  parallel,  or  very  nearly  so, 
especially  where  there  are  more  than  two.  As  previously  stated, 
there  is  a  slight  natural  movement  to  the  roots  of  which  advantage 
can  be  taken  to  help  hold  the  bridge  firmly  in  position,  and  the 
abutments  may  be  very  slightly  converging  or  diverging,  so  that 
there  will  necessarily  be  a  slight  spring  to  them  in  placing  the 
bridge  in  the  mouth;  but  this  movement  must  be  very  slight, 
otherwise  it  would  result  in  the  loosening  of  the  teeth. 

In  i^aralieling  a  series  of  abutments,  the  start  should  always 


208 


BRIDGE-WORK 


be  made  with  the  smallest  and  the  others  paralleled  to  that  one, 
especially  if  this  small  abutment  is  an  anterior  root  in  which  a  pin 
or  tube  is  to  be  used.  The  object  of  doing  this  can  readily  be  seen 
by  studying  the  illustration.  If  one  of  the  abutments  is  a  lateral 
incisor  and  another  a  cuspid  or  a  tooth  on  which  is  to  be  placed  a 
shell  or  telescope  crown,  the  lateral  being  a  very  small  root  allows 
very  little  leaway  in  placing  the  post  or  tube,  as  the  canal  must 
necessarily  be  enlarged  on  its  original  line.  If  a  cuspid  is  used  as 
another  anchorage,  the  root  is  of  sufficient  size  so  that  the  canal 
can  easily  be  sloped  to  one  side  or  another  to  make  it  parallel  with 
the  lateral  abutment,  as  shown  in  Fig.  330.  Should  one  of  the 
other  abutments  be  a  shell  crown,  the  stump  can  readily  be  ground 
on  one  side  or  another  to  make  it  parallel  with  the  lateral  or 
bicuspid  abutment  (Fig.  331). 


Fig.  332 


THE   WEINSTEIN   PARALLELING   DEVICE. 

Mr.  L.  J.  Weinstein's  paralleling  device  is  essentially  practical. 
The  mechanical  construction  is  very  simple  and  it  combines  ease 
of  manipulation  with  perfect  accuracy.  Its  range  of  adaptability 
is  far  greater  than  anything  else  available  up  to  the  present  time. 
The  device  consists  of  an  arch  of  steel,  perforated  at  intervals  as 
shown  in  the  illustration  (Fig.  332).  In  these  holes  are  fitted 
studs,  held  in  place  with  collar,  and  nut  with  spring  giving  constant 
tension.     Through  the  square  opening  in  the  top  of  this  stud  is 


THE  WEINSTEIN  PARALLELING  DEVICE 


209 


passed  a  hollow  square  bar  with  a  V  cut  in-  one  end.  Through 
this  bar  is  passed  a  round  rod  with  a  hole  in  one  end  to  receive  the 
mandrel,  the  other  end  being  threaded  to  receive  a  knurled  nut. 

The  mandrel  is  placed  in  the  hole  in  the  rod  and  the  nut  tightened, 
drawing  it  into  the  Veed  end  of  the  hollow  bar  and  holding  it  per- 


FiG.  333 


^Kd^ 

■ 

^ 

fM 

1 

n 

Im 

^^^^B^^^^^BBfcBtt;T!/v 

^^ 

g^^gs^^HH^H 

Fig.  334 


fectly  rigid.  This  bar  can  be  nio\cd  horizontally  in  any  direction 
and  locked  in  place  by  tightening  the  nut  on  the  stud  on  the 
underside  of  the  arch.  The  device  will  accommodate  any  required 
numlx-r  of  the  mandrel  holding  rods  and  several  abutments  can 
be  paralleled  simultaneously.  The  caj)s  can  be  placed  on  the 
14 


210 


BRIDGE-WORK 


roots,  the  tubes  on  the  mandrels  and  after  entering  them  in  the 
canals  they  can  be  waxed  to  the  caps,  removed  and  soldered. 

Another  method  is,  after  placing  the  tubes  in  position,  to  take 
an  impression,  covering  the  ridge,  caps  and  mandrels  with  plaster. 
After  the  plaster  has  hardened,  the  impression  is  removed  from 
the  mouth,  with  the  caps  and  tubes  in  place,  as  shown  in  Figs. 
333  and  334.  The  impression  is  removed  from  the  paralleling 
device  by  loosening  the  nuts  at  the  end  of  the  square  rods  and 
withdrawing  the  mandrels  from  the  holders.  The  caps  and  tubes 
are  then  waxed  from  the  under  side  in  the  manner  already  described, 
the  impression  varnished  and  a  model  prepared,  and  the  waxing 


Fig.  335 


of  the  tubes  to  the  caps  is  done  on  this  model.     The  caps  and 
tubes  are  then  removed,  invested  and  soldered. 

Fig.  335  shows  the  manner  of  paralleling  posterior  abutments 
to  an  anterior  abutment,  either  in  the  mouth  or  on  the  model. 
The  mandrel  is  fitted  in  the  tube  in  cuspid  root  and  locked  to  the 
arch.  Another  mandrel  is  locked  tightly  in  a  holder  distally  but 
the  nut  locking  the  bar  to  the  arch  is  tightened  only  enough  to 
hold  the  mandrel  holder  in  proper  position  so  as  to  allow  of  easy 
movement  in  a  horizontal  direction.  The  mandrel  in  the  cuspid 
tube  rotating  freely,  allows  the  other  mandrel  to  move  freely  to 
any  point  so  that  the  molar  or  bicuspid  caps  are  easily  adjusted. 


OCCLUSION 


211 


The  paralleling  device  outfit  consists  of  two  arches  (sn:all  and 
large)  and  the  necessary  mandrel  holders,  a  gauge  for  quickly 
neasuring  the  diameter  of  mandrels  or  tubes  and  a  number  of 
non-nisfing  mandrels,  one-half  to  one-thousandth  of  an  inch  smaller 
than  the  hardened  steel  m.andrels  o^•er  which  the  platinum  tubes 
fit  snugly.  These  mandrels  are  very  useful  as  they  will  not  rust 
from  contact  with  saliva,  or  when  being  exposed  to  the  air,  and 
being  just  a  trifle  sm.aller,  go  in  and  out  of  the  tubes  easily,  whereas, 
the  hardened  steel  mandrels,  over  which  the  tubes  are  made  or 
drawn,  must,  of  necessity,  fit  quite  snugly. 

All  the  parts  of  the  paralleling  device  are  rust-proof  so  that  it 
is  not  aft'ected  bv  moisture. 


Fig.  ."536. — Upper  and  lower  teeth  in  occlusion.     (From  photoKniph  of 
specimen  in  the  Wistar  Institute  of  Anatomy.) 


OCCLUSION. 

In  addition  to  its  other  rccpiircmcnt.  the  occlusion  of  a  bridge 
piece  must  be  as  nearly  jjerfect  as  it  is  possible  to  make  it.  This  is 
a  most  important  consideration  and  one  to  which  too  little  atten- 
tion is  generally  given.  A  bridge  which  properly  occludes  with 
the  ofjpositig  teeth  will  not  only  be  more  effective  than  one  faulty 
in  this  resijcct,  but  its  nse  will  be  attended  with  liir  less  liability 
of  loosening  or  injuring  of  the  iibiitnients. 


212 


BRIDGE-WORK 


A  large  percentage  of  the  cases  of  bridge-work  are  for  the  posterior 
part  of  the  mouth,  the  dentist  being  most  frequently  called  upon  • 


Fig.  337. — Occlusion  of  the  incisor  teeth.     (From  photograph  of  specimen 
No.  4237,  Wistar  Institute  of  Anatomy.) 


Fig.  338. — Occlusion  of  the  molar  and  bicuspid  teeth,  external  view.     (From 
photograph  of  specimen  in  possession  of  the  author.) 

to  restore  lost  molars  and  bicuspids.    Where  these  teeth  in  either 
jaw  have  been  lost  for  any  length  of  time,  their  antagonists  in  the 


OCCLUSION 


213 


opposite  jaw  are  sure  to  have  elongated  to  a  greater  or  less  extent 
(Fig.  340),  and  if  no  measure  is  undertaken  to  prevent  it,  they  will 
eventuallv  be  exfoliated.      The  normal  line  of  occlusion  must  be 


Fig.  339. — Occlusion  of   the  molar  and   bicuspid  teeth,  internal  view.      (From 
photograph  of  specimen  in  possession  of  the  author.     Same  specimen  as  Fig.  338.) 

restored  in  such  cases,  if  a  satisfactory  denture  is  to  be  made  to 
replace  the  lost  teeth,  whether  it  be  a  i)late  or  a  bridge.    If  a  bridge 


Vu;.  340 


Fk;.  341 


is  constructed  without  doing  this,  it  can  nc\cr  be  as  scr\iceablc  to 
the  patient  as  where  the  occlusion  has  been  made  normal.  The 
triturating  motion,  so  necessary  for  the  perfect  pcrforniiiiice  of  the 


214  BRIDGE-WORK 

masticatory  function,  is  interfered  with  or  altogether  lost,  the  only 
movements  possible  being  the  opening  and  closing  of  the  jaws,  in 
which  case  the  food  may  be  pressed  or  crushed,  but  not  ground. 
The  moment  the  mandible  is  thrust  the  least  bit  forward,  the  jaws 
are  thrown  apart  and  the  only  point  of  contact  is  the  distal  cusp 
of  the  elongated  molar,  with  the  mesial  cusp  of  the  lower  molar 
opposite  (Fig.  341). 

Where  this  elongation  of  the  teeth  has  taken  place,  they  must 
be  ground  to  the  normal  line  of  occlusion  and  the  teeth  carved  so 
as  to  reproduce,  as  nearly  as  possible,  the  original  cusps.  If  they 
have  become  very  much  elongated,  it  may  be  necessary  to  devitalize 
and  crown  them,  or  to  restore  their  masticating  surfaces  by  building 
up  with  gold  or  porcelain. 

SELECTION    OF    FACINGS. 

In  choosing  facings  or  crowns  for  a  crown  or  a  bridge,  or  in  fact 
for  any  form  of  partial  denture,  the  greatest  care  should  be  exer- 
cised to  select  those  of  proper  mold  and  shade.  If  it  is  impossible 
to  get  a  facing  to  match  exactly,  it  is  better  that  it  should  be  slightly 
darker  in  shade  rather  than  lighter  than  that  of  the  natural  teeth. 
If  a  crown  is  the  least  particle  too  light  in  color  it  is  conspicuous, 
and  is  the  first  tooth  seen  when  the  patient  opens  the  mouth,  while 
if  it  is  but  slightly  darker  than  the  neighboring  teeth  it  is  not  so 
noticeable. 

In  restoring  the  six  anterior  teeth,  the  facings  should  not  be 
bought  in  sets  as  put  up  by  the  manufacturers.  In  the  human 
mouth,  these  teeth  are  never  all  of  the  same  shade.  The  central 
incisors  have  generally  a  yellowish  cast.  The  laterals  are  of  the 
same  general  shade  but  are  clearer  at  the  tip  with  a  slight  bluish 
tint,  while  the  cuspids  are  the  yellowest  teeth  in  the  mouth  anterior 
to  the  molars.  If  the  facings,  restoring  these  teeth,  are  all  of  one 
color,  they  will  not  present  a  natural  appearance,  since  their 
uniformity  of  color  will  at  once  advertise  their  artificial  nature. 
They  should  be  selected  in  pairs,  the  centrals,  lateral  and  cuspids, 
each  from  a  different  set  in  accordance  with  the  natural  shading 
of  these  teeth,  but  the  blending  should  be  perfect. 

As  we  go  farther  back  in  the  mouth  we  find  the  bicuspids  are 
more  on  the  order  of  the  lateral  incisors,  being  clearer  at  the  tips 
and  of  a  slightly  bluish  tint,  while  the  molars  are  generally  yellow. 
In  selecting  these  teeth,  the  bicuspids,  especially  the  first,  should 


FIXED  BRIDGES 


215 


be  matched  as  nearly  as  possible.  With  the  molars  there  is  not 
the  same  necessity  for  being  so  exact.  They  should  be  of  the 
same  general  shade  and  blend  well,  but  may  be  darker  than  the 
natural  teeth,  but  in  no  case  should  they  be  lighter. 

The  shapes  of  the  teeth  also  should  be  studied  carefully,  and  the 
form  of  those  lost  should  be  reproduced  as  nearly  as  possible  by 
their  substitutes.  The  types  of  teeth  vary  greatly,  some  having  a 
broad  flat  face,  others  being  very  much  rounded  (Figs.  342  and 
343).     Again,  it  will  be  found  that  some  are  nearly  flat  from  the 


Fig.  .342 


Fig.  343 


Fig.  344 


Fig.  345 


incisal  edge  to  the  gingiva  while  others  are  decidedly  convex,  as 
in  Figs.  344  and  345.  Where  one  of  these  types  prevail  a  corre- 
sponding tooth  to  replace  it  or  its  mate  should  always  be  selected. 
The  remaining  natural  teeth  will  serve  as  an  index  for  the  form 
i)f  the  selected  crowns  or  facings. 

FIXED   BRIDGES. 

In  considering  the  construction  of  a  fixed  bridge,  as  a  common 
type,  one  which  might  be  called  a  skeleton  bridge  will  be  selected, 
one  in  which  two  full  gold  crowns  or  a  full  gold  crown  and  a  porce- 
lain-faced crown  are  to  serve  as  abutments,  carrying  one  or  more 
dummies,  the  occlusal  and  lingual  surfaces  being  of  gold,  and  using 
porcelain  veneers  simply  for  esthetic  effect  (Figs.  34()  and  347). 


I..- 


Fi(i.  340 


Fig.  347 


The  bands  or  caps  having  been  adjusted  in  their  resi)ective 
positions  in  the  mouth,  the  impression  and  articulation  are  taken, 
and  the  model  is  preparerl  in  the  maimer  already  described.  The 
shell  crowns  are  c()mi)lct('d  aixl  articulated  aii<l  are  then  ready  for 
the  facint:s. 


216 


BRIDGE-WORK 


In  selecting  the  facings  for  the  case,  it  is  desirable  to  choose 
them  of  such  length  that  when  they  are  ground  into  place,  the  necks 
will  touch  the  gum  lightly  and  the  occlusal  edges  will  be  in  contact 
with  the  antagonizing  teeth  (Fig.  348).  They  are  ground  to  follow 
the  gum  line  and  should  set  very  close  to  each  other,  but  should 
not  be  in  actual  contact  (Fig.  347).  After  they  have  been  ground 
into  place,  a  wall  of  plaster  is  built-up  on  the  buccal  side  of  the 
model,  nearly  to  the  occlusal  or  incisal  ends  of  the  facings,  to  retain 
them  in  position  (Fig.  348) . 


Fig.  348 


Fig.  349 


After  the  plaster  has  hardened,  the  facings  are  removed,  and 
their  occlusal  ends  ground  off  about  one  thirty-second  of  an  inch 
and  at  an  angle  of  about  forty-five  degrees  with  the  back  of  the 
facing  (Fig.  349).  The  line  of  their  occlusal  ends  should  be  con- 
tinuous, that  is,  the  bevel  of  one  facing  should  not  be  higher  than 
another. 

The  facings  are  then  backed,  and  for  this  purpose,  platinum, 
crown  metal  or  pure  gold  may  be  used.  The  gold  will  have  a  ten- 
dency to  lighten  the  color  of  the  facing  and  give  it  a  slightly  yellower 


Fig.  350 


Fig.  351 


cast,  while  the  platinum  will  tend  to  darken  it  and  confer  a  bluish 
tint.  If  the  backing  is  of  platinum  or  crown  metal,  it  may  be  very 
thin,  about  three  one-thousandths  of  an  inch.  It  should  extend  from 
the  inner  edge  of  the  bevel  at  the  occlusal  end,  to  about  one-sixteenth 
of  an  inch  beyond  the  lower  edge  where  it  has  been  ground  to  fit  the 


FIXED  BRIDGES 


21: 


gum  (Fig.  350) .  The  backing  of  each  facing  should  touch  or  sUghtly 
o\erlap  that  of  the  one  next  adjoining  and  those  of  the  end  facings 
should  be  in  contact  with  the  abutment  crowns  (Fig.  351). 

The  pins  are  flattened  with  a  pair  of  pin-roughing  pliers,  and  are 
bent  down  over  the  backing,  thus  pressing  it  close  to  the  facing. 
The  facings  are  then  waxed  together  and  to  the  abutment  crowns 
with  hard  adhesive  wax,  a  piece  of  oiled-paper  being  placed  under- 


FiG.  352 


Fig.  3.53 


neath  on  the  surface  of  the  cast  to  prevent  the  wax  from  adhering 
to  it.  The  wax  should  be  built  up  high  enough  to  support  the 
cusps  for  the  dummies  (Fig.  352).  Suitable  solid  cusps  are  then 
made,  ground  or  filed  to  fit  the  bevel  of  the  facings,  and  fastened 
in  place  with  adhesive  wax  (Fig.  353).  • 

The  bridge  is  now  ready  for  investing  and  soldering.  It  is  taken 
from  the  model,  and  the  inside  of  the  abutment  pieces  filled  with 
the  investing  material  and  the  whole  bridge  partly  imbedded  in 
it  with  the  facings  down.  The  investment  should  come  over  the 
backings  which  extend  beyond  the  lower  angle  of  the  facings,  hold- 
ing them  in  place  and  preventing  their  springing  up  under  heat 
(Fig.  354,  a),  and  nearly  to  the  lingual  edge  of  the  cusp  (Fig.  354,  h) 


Fig.  3.'>6 


Fig.  3.54 


Fig.  355 


Fig.  357 


and  should  be  small,  large  enough  only  to  hold  the  parts  securely 
together.  The  abutment  crowns  are  partly  covca-ed  to  protect 
them  horn  the  Hame. 

In  grinding  the  facings  of  the  dummies  for  an>-  of  the  six  anterior 
teeth,  they  should  be  made  to  set  closely  to  the  model,  and  after 
they  are  properly  fitted  a  wall  of  plaster  is  made  011  the  labial  side. 


218  BRIDGE-WORK 

The  facings  are  then  backed,  the  backings  extending  over  the 
beveled  portion  at  the  neck  and  about  one-sixteenth  of  an  inch 
beyond  the  incisal  edge  and  the  pins  flattened  and  bent  toward  this 
edge  close  to  the  backing  (Fig.  355).  In  investing,  the  investment 
should  cover  the  extending  portions  of  the  backing,  both  at  the 
incisal  and  gingival  ends,  to  prevent  its  warping  (Fig.  356). 

After  investing,  a  wire  of  coin  gold  should  be  fitted  to,  and  laid 
over,  the  backings  at  the  gingival  edge  as  shown  in  Fig.  357,  so  that 
in  soldering,  the  lingual  side  may  be  built  up  more  nearly  to  the 
normal  contour  of  the  tooth. 

Bridges  of  three  or  four  teeth  may  be  soldered  in  one  piece,  but 
large  cases  should  be  soldered  in  sections,  because  the  contraction 
of  large  masses  of  solder,  when  the  piece  is  cooling,  has  the  effect 
of  disturbing  the  relation  of  the  abutment  pieces,  and  in  conse- 
quence the  fit  of  the  bridge  is  impaired.  A  full  bridge  of  twelve  or 
fourteen  teeth  should  be  soldered  in  three  or  four  sections.  If  in 
three,  the  incisors  may  be  soldered  in  one  piece,  and  the  sides, 
from  the  cuspids  back,  separately.  If  in  four  sections,  the  central, 
lateral  and  cuspid  of  each  side  may  be  soldered  separately,  and 
also  each  side  sections. 

The  different  sections  are  finished  and  polished  except  where 
they  are  to  be  united.  They  are  then  replaced  on  the  model,  waxed 
together  with  adhesive  wax,  and  a  strong  iron  or  brass  wire  bent 
to  conform  to  the  lingual  side  of  the  bridge  and  thoroughly  waxed 
to  the  different  parts.  This  will  hold  them  firmly  in  their  relative 
positions,  and  prevent  their  springing  while  being  removed  from 
the  model  and  invested.  The  bridge  is  then  invested,  the  divisions 
between  the  several  sections  being  freely  exposed  and  the  parts 
united  with  the  same,  or  a  slightly  lower  carat  solder  than  has  been 
used  in  the  previous  soldering.  When  the  investment  has  cooled, 
the  bridge  is  removed,  pickled  in  dilute  sulphuric  acid,  and  finished. 

Interchangeable  Facings. — In  using  interchangeable  facings  of  the 
Steele  or  Evslin  type  (Figs.  354  and  355),  the  facings  are  ground  in 
as  are  the  ordinarj^  pin-facings,  and  afterward  a  wall  of  plaster  is 
built  around  them,  reaching  nearly  to  the  incisal  edges.  The  back- 
ings are  then  fitted  and  should  be  carried  a  little  beyond  the  incisal 
edge.  The  backings  should  be  made  so  that  they  will  come  in 
contact  with  each  other,  after  which  they  are  waxed  firmly  together 
with  hard,  sticky  wax,  a  heavy  iron  or  brass  wire  being  laid  across 
the  lingual  side  of  the  backings  to  prevent  their  becoming  distorted 
in  removing  the  facings  and  investing. 


PIXED  BRIDGES 


219 


After  the  facings  are  removed,  it  is  well  to  give  the  labial  side 
of  the  backings  a  coating  of  anti-flux  (whiting  may  be  used  for  this 
purpose)  before  investing.  This  will  tend  to  prevent  any  solder 
from  flowing  on  that  side  of  the  backings. 


Fig.  35S 


Fig.  359 


Fig.  360 


They  are  then  invested,  labial  face  down,  and  should  lay  nearly 
level.  After  the  wax  has  been  removed  a  heavy  gold  wire,  prefer- 
ably square,  should  be  fitted  along  the  gingival 
edge  of  the  backings,  as  in  Fig.  360,  and  the  piece 
heated  up  for  soldering.  Twenty  or  twenty-one 
carat  solder  should  be  used  for  soldering,  and 
the  solder  built  up  so  as  to  restore  as  nearly  as 
possible  the  normal  lingual  surfaces  of  the  teeth, 
leaving  it  thick  at  the  incisal  edge.  It  will  be  found  that  the 
wire  across  the  base  of  the  backings  will  very  materially  aid  in 
giving  form  to  the  backs.  The  piece  is  then  cleansed  and  finished. 
In  finishing  a  bridge  of  this  character,  it  is  well  to  outline  and 
contour  the  lingual  surfaces  of  each  tooth  restored  so  that  they 
will  resemble  the  lingual  surfaces  of  the  natural  teeth  as  nearly  as 
possible  and  j)resent  a  more  artistic  efl'ect,  and  consefjuently  a 
much  more  comfortable  feeling  to  the  tongue. 

In  finishing  the  incisal  edges  of  the  backings,  the  facings  should 
first  ])v  replaced  and  then  the  backings  ground  from  the  labial 
side  flush  with  the  facings  at  that  point  and  extend- 
ing a  little  upward  on  the  lingual  side,  as  in  Fig. 
'MW ,  so  that  the  backing  will  be  a  little  longer  at 
this  j)()int  and  will  protect  the  facings.  The  gold 
should  be  left  as  thick  as  the  bite  will  allow  at 
Fig.  :mi  the  incisal  edge  so  as  to   protect   the  facings  and 

lessen  the  liability  of  their  being  broken.  Such 
facings  are  nnich  weaker  than  are  the  ordinary  pin-facings,  and  for 
this  reason,  it  is  always  best  to  prepare  duplieates  which  may  be 


2'20  BRIDGE-WORK 

used  in  case  of  an  accident.  In  any  event,  the  shades  and  mold  of 
the  crowns  or  facings  used  should  be  placed  on  record.  In  grinding 
in  the  duphcates,  whether  crowns  or  facings,  they  should  be  made 
very  exact  so  that  if  it  were  necessary  to  replace  one,  the  duplicate 
could  not  be  told  from  the  original.  Each  crown  should  be  ground 
separately,  with  all  of  the  others  in  position. 

If  duphcates  are  to  be  made  of  the  six  anterior  teeth,  they  should 
be  taken  one  at  a  time,  removing  the  cuspid  first  and  grinding  in 
the  duphcate  cuspid  so  that  it  exactly  corresponds  with  the  original. 
After  this  has  been  completed,  the  original  cuspid  is  replaced  and 
the  lateral  removed  and  the  duplicate  lateral  ground  in,  After 
which  the  original  lateral  is  replaced  and  the  central  removed  and 
the  new  one  ground  in  place  and  so  on  until  duplicates  of  the 
entire  set  have  been  made. 

In  this  way  as  many  duplicates  as  may  be  desired  can  be  made 
with  the  knowledge  that  they  are  all  absolutely  interchangeable. 
This  same  order  should  be  followed  whether  facings  or  crowns 
are  being  used. 

EXTENSION   BRIDGES. 

In  a  very  large  majority  of  the  smaller  extension  bridges  which 
are  made,  where  the  whole  or  a  portion  of  the  body  of  the  bridge 
extends  beyond  the  single  abutment,  as  in  Figs.  362  and  363,  the 
entire  principle  -is  faulty  and  the  whole  piece  a  mechanical  impos- 
sibility. Notwithstanding  this,  pieces  of  this  description  are  placed 
in  mouths  to  the  detriment  of  the  patients.     Sooner  or  later  the 


Fig.  362  Fig.  363  Fig.  364 

abutments  to  which  these  pieces  are  anchored  are  sure  to  be  forced 
out  of  their  normal  position  and  frequently  are  lost.  In  the 
anterior  part  of  the  mouth,  where  an  appliance,  such  as  shown' in 
Fig.  363  has  been  inserted,  the  rotation  and  consequent  loosening 
of  the  root  is  inevitable. 

In  Fig.  364,  where  a  dummy  having  an  occlusal  surface  is  attached 
to  a  single  abutment  there  is  not  only  a  strong  lateral  strain  which 


THE   USE  OF  PORCELAIN  CROWNS  IN  BRIDGE-WORK       221 

will  give  a  constant  twisting  motion  to  the  root,  but  there  is  also 
a  direct  force  which  is  being  continually  exerted,  gradually  tilting 
the  abutment  and  forcing  the  dummy  into  the  tissues  (Fig.  364) 
with  the  resultant  loss  of  occlusion  and  the  eventual  loss  of  the 
tooth  to  which  the  bridge  is  attached. 

One  inflexible  rule  applies  in  all  of  these  cases  and  that  is  that 
there  must  always  be  a  support  at  each  end  of  a  bridfje  and  never 
under  any  consideration  should  a  single  point  (f  attachment  be 
depended  upon  to  carry  a  dummy. 

A  small  spur  of  platinized  gold  or  iridio-platinum,  attached 
to  the  lingual  side  of  the  dummy,  and  resting  in  a  small  gold  filling 
or  inlay  on  the  lingual  side  of  an  adjoining  tooth,  as  shown  in  Fig. 
365,  will  entirely  overcome  the  possibility  of  rotation,  and  will 
make  the  piece  a  permanent  fixture  rather  than  a  temporary  one. 


Fig.  365  Fig.  360 

A  spur  resting  in  the  lingual  side  of  the  cuspid  or  in  a  filling  or 
inlay  in  the  fissure  of  a  molar  or  bicuspid  (Fig.  366),  will  effectu- 
ally prevent  future  trouble  and  render  a  piece  serviceable  which 
would  otherwise  be  worthless. 

Extension  Bridges  with  Saddles. — Extension  bridges,  in  which 
saddles,  resting  on  the  ridge,  are  employed  as  an  additional  sui)port 
should  never  be  used  in  fixed  bridges,  as  it  is  impossible  to  properly 
cleanse  an  appliance  of  this  kind.  Irritation  and  inflammation 
are  sure  to  ensue,  and  its  use  will  sooner  or  later  result  in  the  loss 
of  the  abutment  teeth,  if  not  in  troubles  of  a  more  serious  nature. 

THE  USE  OF  PORCELAIN  CROWNS  WITH  SOLDERED  BASE  IN 
FIXED  BRIDGE  WORK. 

Where  porcelain  crowns  are  used  in  fixed  bridge-work,  there 
must  be  a  deptli  of  bite  great  enough  to  allow  a  sufficient  mass  of 
metal  beneath  the  crowns  to  give  strength  and  stability  to  the 
appliance,  and  at  the  same  time  allow  of  space  enough  on  the 
lingual  side  between  the  base  and  the  gum  to  permit  of  properly 
cleansing  the  piece.     In  any  of  the  six  anterior  teeth,  unless  there 


222  BRIDGE-WORK 

has  been  a  great  resorption  of  tissue,  the  dummy  crowns  should  be 
ground  so  that  they  will  rest  on  the  gum  at  the  labial  side,  but  be 
freely  clear  of  the  gum  on  the  lingual,  as  in  Fig.  367a. 

After  the  crowns  have  been  properly  ground  and  arranged  on 
the  model,  a  wall  of  plaster  should  be  built  up  on  the  labial  side 
so  as  to  retain  them  in  position  (Fig.  367  b).    The  lingual  side  and 


Fig.  367  Fig.  368  Fig.  369 

on  the  mesial  and  distal  about  half  or  two -thirds  the  way  to  the 
labial  should  be  beveled  in  order  that  the  bases  may  come  up  over 
the  edges  of  the  crowns  at  these  points  and  form  a  positive  seat  in 
which  the  crowns  may  rest  (Fig.  368).  They  should  all  be  ground 
symmetrically  and  on  line  one  with  another  so  that  one  will  not 
stand  conspicuously  above  its  mates. 

The  foregoing  will  apply  to  the  preparation  of  crowns  for  the 
posterior  part  of  the  mouth  when  the  depth  of  the  bite  is  not  too 
great. 

The  bases  for  the  crowns  of  pure  gold,  No.  35  or  36  guage,  are 
first  made.  These  may  be  fitted  by  swaging  or  burnishing,  the 
gold  extending  up  over  the  beveled  edges  of  the  crowns.  Openings 
are  made  through  the  floors  of  the  bases  and  through  these  openings 
posts  of  platinized  gold  are  fitted.  These  are  then  waxed,  removed, 
invested,  and  the  posts  soldered  to  the  bases  from  the  under  side 
with  a  little  piece  of  coin  gold  (Fig.  369).  They  are  then  replaced 
on  the  crowns,  properly  assembled  on  the  model  and  waxed  firmly 
together.  It  is  a  good  plan  to  lay  a  piece  of  heavy  iron  or  brass 
wire  across  the  bases  and  wax  it  firmly  to  prevent  their  changing 
position  while  investing.  The  crowns  are  then  removed  and  the 
bases  invested,-  leaving  the  under  surface  well  exposed.  It  will 
assist  materially  in  soldering,  if  a  small  wire  of  coin  gold  is  placed 


THE   USE  OF  PORCELAIN  CROWNS  IN  BRIDGE-WORK       223 

throughout  the  length  of  the  piece  on  the  Hngual  iside  and  the 
solder  built  up  to  that  (Fig.  370). 


Fig.  370  Fic.  371 

After  soldering,  the  piece  is  cleansed  in  acid,  polished  and  finished, 
except  at  the  points  where  it  is  to  be  united  to  the  abutment  caps 
(Fig.  371 ).  The  crowns  are  then  put  in  place  on  their  bases  and  care- 
fully adjusted  on  the  model,  and  the  bases  waxed  carefully  to  the 
abutment  caps.  The  crowns  are  then  removed  and  the  abutment 
caps,  together  with  the  crown  bases,  are  invested  and  united  with  20- 
or  21-carat  solder.  After  the  piece  has  been  cleansed  and  polished, 
it  is  ready  for  the  cementing  of  the  crowns.  The  pin  holes  in  the 
crowns  are  filled  with  cement,  as  are  the  bases,  and  the  crowns 
are  forced  into  place  and  kept  under  pressure  until  the  cement  has 
well  hardened,  after  which  the  excess  of  cement  is  trimmed  away 
and  the  l)ridgc  is  ready  for  the  mouth. 

Use  of  the  Cast  Base. — If  the  bases  are  to  be  cast,  posts  of  plat- 
inized gold  may  be  fitted  into  the  post-holes  in  the  crowns,  or  the 
posts  may  be  made  at  the  same  time  the  base  is  cast,  by  forcing 
a  small,  pointed  piece  of  inlay  wax  in  the  hole  in  the  base  of  the 
crown  and  this  being  united  with  the  wax  base  becomes  a  part  of 
the  casting.  The  bases  of  the  crown  should  be  lubricated  with 
cocoa  butter  or  glycerin,  and  a  piece  of  tin  foil  or  oiled  paper 
fitted  over  the  ridge  to  protect  the  model  from  the  wax  and  permit 
of  their  easy  removal,  and  the  space  between  the  crowns  and  the 
paper  filled  in  with  inlay  wax,  after  which  it  is  removed  and  carved, 
cutting  awa\'  enough  of  the  wax  on  the  under  side  lingually  so 
that  it  will  clear  the  gum  sufficiently  for  cleansing  i)urposes. 

The  crowns  should  be  removed  and  replaced  several  times  to 
make  sure  that  they  are  perfectly  free. 

If  there  should  be  not  more  than  two  or  three  bases  to  be  made 
they  may  be  cast  in  one  piece.  If  the  four  incisors  are  to  be  restored 
it  is  better  to  divide  the  base  at  the  median  line  and  cast  the  two 
halves  separately,  afterward  uniting  them  with  solder. 

The  sprue  wire  is  firmly  attached  to  the  lingual  side,  and  this 
should  be  done  before  fiFially  removing  the  crowns,  so  that  there 


224  BRIDGE-WORK 

is  no  likelihood  of  distorting  the  wax  on  the  inside  of  the  base 
(Fig.  372). 

In  the  posterior  part  of  the  mouth,  where  the  gold  is  not  likely 
to  show,  the  bases  may  be  carried  through  to  the  buccal  side,  and 


Fig.  372  Fig.  373 

in  such  cases  the  base  of  the  crowns  are  beveled  slightly  all  around 
so  that  they  may  be  firmly  seated.  They  should  be  cut  high  on  the 
lingual  side,  the  same  as  the  anterior  crowns,  for  cleansing  purposes 

(Fig.  373). 


CHAPTER  XII. 
REMOVABLE  BRIDGE-WORK. 

WiiH  the  advent  of  removable  appliances,  the  possibilities  of 
bridge-work  have  been  greatly  increased.  The  field  of  operations 
has  been  extended  so  as  to  include,  not  only  many  cases  where 
fixed  bridges  have  been  worn,  but  also  a  great  many  others  where, 
up  to  that  time,  the  only  hope  of  the  patient  was  a  plate,  more  or 
less  satisfactory. 

The  advantages  of  removable  bridge-work  o\er  fixed  bridges 
are  many,  and  it  is  very  questionable  whether  there  is  a  single 
instance  where  fixed  bridge-work  answers  the  purpose  better  than 
removable.  It  is  undoubtedly  true  that  in  almost  every  case  where 
fixed  bridge-work  has  been  placed,  removable  bridge-work  could 
have  been  used  to  a  much  better  advantage  and  would  have  given 
far  greater  satisfaction  to  the  patient.  Then  again,  there  are  many 
cases  where  conditions  are  such  that  a  removable  bridge  is  indicated, 
where  a  fixed  bridge  should  not  be  thought  of. 

From  a  hygenic  point  of  view,  there  can  be  no  question  as  to 
which  is  the  best.  A  removable  piece  can  be  taken  from  the  mouth 
and  thoroughly  cleansed  and  sterilized  by  boiling  or  any  other 
method  which  the  patient  may  desire.  When  the  bridge  has  been 
removed,  the  abutment  caps,  being  i)erfectly  simple  and  easily 
accesible,  can  be  thoroughly  cleansed  at  every  point. 

In  the  case  of. a  bridge  which  is  immovably  fixed  to  its  supports, 
there  are  spaces  and  crevices  in  which  particles  of  foodstufi"  or 
other  material  may  lodge,  which  cannot  be  reached  even  by  the 
dentist.  It  is  impossible  to  thoroughly-  cleanse  and  sterilize  such 
a  briflge,  as  there  is  nothing  which  can  be  taken  in  the  mouth  that 
is  of  sufficient  strength  to  perfectly  cleanse  and  sterilize  it  without 
injury  to  the  soft  tissues. 

Another  advantage,  which  a  removable  bridge  j)ossesses  over 
a  fixed  bridge,  is  the  facility  with  which  it  can  be  repaired  in  case 
of  an  accident.  The  bridge  can  be  removed  and  the  entire  work 
of  re|)airing  can  be  done  in  the  laboratory,  without  the  slightest 
inconvenience  to  the  i>atient.  In  the  case  of  extensixc  (hnnage 
-to  a  fixed  bridge,  it  is  fre(|uently  necessary  to  so  cut  and  nnitilatc 
it,  in  order  to  remove  it  from  tlic  niontli,  as  to  nearly  destroy  it, 
15 


226  REMOVABLE  BRIDGE-WORK 

necessitating,  in  many  instances,  practically  the  making  of  the 
entire  bridge  over  again. 

This  is  especially  true  in  a  case  where  there  are  many  abutments. 
In  making  extensive  restorations,  where  there  are  a  large  number 
of  anchorages,  a  fixed  bridge  should  never  be  placed.  It  may 
at  any  time  happen,  that  in  cementing  a  fixed  bridge  of  this  charac- 
ter, from  one  cause  or  another,  the  cementing  of  one  or  more  of 
the  abutments  has  been  faulty,  and  before  this  is  discovered,  these 
roots  have  been  entirely  destroyed  through  leakage  and  decay. 
It  would  be  impossible  for  this  to  happen  in  the  case  of  removable 
work,  for  should  one  of  the  abutment  caps  become  loosened,  it 
will  manifest  itself  at  once  by  coming  away  with  the  bridge,  in 
which  case  it  can  easily  be  recemented,  rendering  the  piece  as  firm 
as  ever. 

Another  very  decided  advantage  in  a  removable  piece  is  the 
facility  with  which  affected  teeth  adjacent  to  the  bridge  may  be 
treated.  Every  dentist  has  probably  had  the  experience  of  under- 
taking to  place  a  gold  filling  in  an  approximal  cavity  in  a  tooth 
adjoining  a  fixed  bridge. 

rf  the  bridge  be  removable,  it  can  be  taken  from  the  mouth, 
leaving  ample  room  for  any  operation  which  may  be  necessary. 
With  the  advent  of  cast  gold  inlays,  these  operations  have  been 
much  simplified.  The  insertion  of  such  an  inlay  is  not  nearly  so 
difficult  as  was  the  putting  in  of  a  gold  filling  by  the  old  method. 
But  the  fact  remains  that  we  can  much  better  place  an  inlay  if, 
by  the  removal  of  the  bridge,  we  have  ample  room  in  which  to  work. 

The  value  of  removable  bridge-work  depends  entirely  upon 
the  attention  given  to  the  numerous  details,  and  upon  the  accuracy 
with  which  the  work  is  done.  The  fittings  must  be  as  nearly  perfect 
as  it  is  possible  to  make  them,  otherwise  the  work  will  not  prove  a 
success.  The  training  which  one  gets  in  doing  this  class  of  work, 
tends  not  only  to  make  him  more  proficient  in  bridge-work,  but 
more  proficient  in  every  branch  of  the  profession,  as  the  care  and 
skill  required  develops  a  delicacy  of  touch,  and  exactness  in  manipu- 
lation to  a  far  greater  degree  than  does  the  ordinary  routine  of  the 
dental  work-room. 

ATTACHMENTS  TOR  REMOVABLE  BRIDGE-WORK. 

Retaining  and  Supporting  Abutments. — There  are  two  classes  of 
abutments  in  both  fixed  and  removable  bridge-work,  and  these 


RETAINING  ABUTMENTS  227 

are  known  respectively  as  retaining  abutments,  and  supporting 
abutments. 

By  a  retaining  abutment  is  meant  an  abutment  which  not  only 
gives  support  to  the  bridge,  but  also  retains  it  in  its  proper  position 
in  the  mouth,  as  in  the  case  of  a  Richmond  crown,  shell  crown, 
telescope  crown  and  others  of  a  similar  character. 

A  supporting  abutment  is  one  which  gives  support  to  the  bridge, 
but  has  nothing  to  do  with  its  retention.  An  example  of  an  abut- 
ment of  this  kind  would  be  where  a  spur  is  resting  in  a  gold  filling 
or  in  an  inlay  in  an  adjoining  tooth,  and  serving  simply  to  prevent 
anv  lateral  movement  and  to  resist  the  force  of  occlusion. 


RETAINING   ABUTMENTS. 

There  are  many  different  styles  of  attachments  for  removable 
work,  and  the  writer  will  describe  those  which  he  has  found 
most  useful,  and  which  have  the  most  variable  application.  In 
discussing  these  different  attachments,  we  will  first  consider  those 
which  are  most  frequently  indicated  in  the  posterior  part  of  the 
mouth  for  the  molars  and  at  times  for  the  bicuspids.  The  first  of 
these  is  the  telescope  crown. 

The  telescope  crowns  should  not  be  confounded  with  the  shell 
crowns,  which  are  simply,  as  the  name  indicates,  shell  caps  fitted 
to  the  stumps.  The  telescope  crown  is  really  a  crown  in  which 
one  part  telescopes  the  other  with  the  ease  and  accuracy  of  the 
slides  of  a  telescope. 

Telescope  Crown. — This  crown  is  especially  adapted  to  the 
molars,  and  where  great  strengtii  is  required,  or  where  the  gold 
can  be  hidden,  as  far  forward  as  the  second  bicusj)id,  and  at  times 
even  the  first,  but  should  never  be  carried  beyond  the  first  bicuspid, 
and  rarely  to  that  tooth.  The  telescopes  may  be  used  where  there 
are  two  retaining  abutments,  providing  the  telesco])e  can  be  matle 
of  sufficient  length  to  give  a  permanent  and  firm  grij). 

Alloys  Suitable  for  Making  Telescope  Crowns.-  The  alloy  suitable  for 
a  telescope  (Touii  iiiiist  possess  great  tensile  streiigtii  and  rigidity, 
and  also  a  certain  amount  of  elasticity.  I'he  22  carat  gold  alloyed 
with  silver,  which  is  most  connnonly  sold  at  the  dental  de])ots,  is 
altogether  unsuitable  for  this  work,  the  silver  alloy  rendering  it 
.soft,  with  the  result  that  if  this  were  used,  the  strain  which  is 
necessarily  brought  to  bear  on  the  bridge  will  cause  the  gold  to 


228  REMOVABLE  BRIDGE-WORK 

stretch  and  so  render  the  crown  worthless  within  a  comparatively 
short  time. 

The  best  results  have  been  secured  by  using  a  copper  alloy,  and 
the  writer  has  found  the  American  coin  gold,  21.6  carats  fine,  to 
be  the  most  suitable  for  this  purpose.  It  is  tough,  strong  and  rigid, 
and  experience  shows  that  it  will  wear  better  than  any  other  high 
carat  alloy.^ 

It  is  not  necessary,  and  perhaps  not  always  desirable,  that  the 
abutments  for  a  removable  bridge  should  be  exactly  parallel,  but 
they  must  be  very  nearly  so.  The  pericemental  membrane  acting 
as  a  cushion,  permits  of  a  slight  natural  spring  to  the  teeth  which 
can  be  taken  advantage  of  to  help  hold  the  bridge  firmly  in  position. 
If  the  natural  inclination  of  the  teeth  is  such  that  they  diverge 
slightly,  they  can  be  trimmed  and  the  bands  so  fitted  to  them  that 
the  bridge  can  be  made  to  accommodate  this  inclination.  The  result 
will  be  that  as  the  bridge  is  placed  in  position,  the  teeth  are  drawn 
together  very  slightly  and  then  spread  apart  and  resume  their 
normal  position  as  the  bridge  is  forced  home.  If  the  teeth  converge, 
when  the  bridge  is  put  in  position,  they  are  forced  apart  very 
slightly,  resuming  their  normal  position  when  the  bridge  is  in  place. 

This  movement  of  the  teeth,  of  course,  must  be  very  slight,  for 
should  it  be  very  great,  it  would  have  a  tendency  to  loosen  the 
teeth,  but  the  slight  natural  spring  will  do  no  harm,  and  as  before 
stated,  will  help  to  hold  the  bridge  more  firmly  in  its  place. 

In  a  telescope  crown  which  has  been  carefully  and  accurately 
made,  there  will  be  practically  no  wear  even  after  they  have  been 
in  use  for  years.  The  fluids  of  the  mouth  forming  a  coating  which 
protects  the  metal  so  that  there  is  in  reality  no  actual  contact 
between  the  outer  and  inner  caps.  On  the  other  hand,  if  the  fitting 
has  not  been  accurate,  and  there  is  the  slightest  play  between  the 
outer  and  inner  caps,  there  will  be  a  very  decided  friction  which 
will,  in  a  very  short  time,  render  the  piece  worthless. 

The  Technic  of  the  Telescope  Crown. — The  trimming  of  a  tooth 
for  a  telescope  crown  is  done  in  practically  the  same  manner 
as  for  an  ordinary  shell  crown,  being  ground  so  that  the  stump  is 
tapering,  and  being  slightly  larger  a  little  below  the  gum  line, 
the  only  difference  being  that  the  occlusal  surface  should  be  cut 

^  Within  the  past  few  years  Mr.  L.  J.  Weinstein,  of  New  York,  has  been  making 
extensive  experiments  in  dental  alloys  for  this  and  other  work,  and  has  produced  some 
which  gives  excellent  results.  A  chapter  by  him  in  another  part  of  this  work  will 
prove  interesting  and  valuable  reading,  not  only  to  the  crown  and  bridge  specialist, 
but  to  the  general  practitioner  as  well. 


RETAINING  ABUTMENTS  229 

away  a  little  more  than  for  a  shell  crown,  as  there  is  a  greater 
thickness  of  metal  at  the  occlusal  end  in  a  telescope  crown  than 
in  a  shell  crown. 

The  measurement  of  the  stump  is  taken  in  the  manner  described 
directly  across.  The  band  should  be  cut  to  this  measurement,  the 
ends  being  nearly  parallel,  but  not  quite,  flaring  a  little  and  being 
slightly  longer  at  the  gingival  edge  (Fig.  374).     The  length  from 


Fig.  374 


the  occlusal  to  the  gingival  edge  of  the  band  should  be  such  that 
it  will  extend  from  well  beneath  the  gum  line  to  a  little  above  the 
occlusal  end  of  the  stump,  or  nearly  in  contact  with  the  occluding 
teeth. 

The  thickness  of  the  gold  of  which  the  band  is  made  should  be 
number  80  Brown  &  Sharpe  gauge.  One  end  is  beveled  to  a  knife 
edge  and  the  other  overlapped  and  the  two  parts  sweated  together. 
The  band  should  then  be  shaped  carefully  to  conform  to  the  shape 
of  the  stump  and  festooned  accurately  to  follow  the  gum  line,  being 
certain  to  have  it  nearly  parallel  with  other  abutments.  In  shaping 
it  to  the  stump,  care  should  be  used  not  to  wrinkle  the  band,  but  to 
keep  it  perfectly  smooth.  The  gingival  end  should  tlien  be  beveled 
slightly  from  the  outside,  any  feather  edge  which  may  have  been 
turned  over  by  the  scissors  or  the  file  being  remo\ed,  so  that  it 
will  pass  freely  under  the  gum  without  mutilating  it  or  causing 
the  patient  unnecessary  pain.  It  should  be  remembered  that  the 
occlusal  end  of  the  band  should  have  exactly  the  same  shape  as 
the  gingival  end,  or  in  other  words,  the  occlusal  end  of  the  band 
should  follow  parallel  with  the  gingival. 

It  is  important  that  this  be  done  accurately,  for  should  the 
occlusal  end  not  have  the  same  outline  as  the  gingival  end,  if  it  be 
pressed  together  too  much  mesialiy  and  distally,  or  buccally  and 
lingually,  it  will  be  conical  from  this  direction  (I<'ig.  875),  but  will 
be  forced  out  at  the  occlusal  end  at  the  other  sides,  giving  it  a 
flaring  top  which  would  render  it  impossible  to  perfectly  fit  the 
outer  band  fFig.  87()). 


230  REMOVABLE  BRIDGE-WORK 

The  band  is  then  placed  on  the  stump,  forcing  the  gingival 
edge  to  nearly  one-sixteenth  of  an  inch  below  the  gum  line.     An 


Fig.  375  Fig.  376 

impression  is  then  taken  and  a  model  prepared  in  the  manner  which 
has  been  already  described.  After  the  model  has  been  separated 
from  the  impression  and  neatly  trimmed,  the  band  may  be  removed 
by  grasping  it  with  a  pair  of  heated  pliers.  The  model  should 
then  be  thoroughly  dried,  treated  with  several  coats  of  thin  sandarac 
varnish  and  then  again  dried  to  harden  it  before  proceeding  with 
the  work.  This  being  done,  the  band  is  replaced  on  the  stump, 
and  enough  of  it  cut  from  the  occlusal  end  to  allow  for  a  thick 
strong  cusp.  The  extreme  occlusal  edge  of  the  band  is  then 
turned  inward  slightly  all  around  (Fig.  377),  care  being  taken  to 
keep  the  edge  parallel  with  the  gingival  end  of  the  band. 

The  object  of  turning  the  edge  of  the  band  in,  is  to  give  this 
end  of  the  cap  a  slightly  rounded  form  in  order  to  facilitate  the 
placing  of  the  bridge  over  it  in  the  mouth.  If  this  were  not  done, 
and  the  top  of  the  cap  was  left  with  a  sharp,  square  edge  all 
around,  it  can  readily  be  seen  by  the  illustration  (Fig.  378),  that  if 


Fig.  .377  Fig.  378  .  Fig.  379 

the  abutments  were  the  least  out  of  parallel,  the  edge  of  the  outer 
cap  would  catch  on  this  square  edge  and  render  the  insertion  of  the 
bridge  very  difficult.  If  the  top  edge  of  the  cap  is  rounded  slightly, 
the  outer  cap  will  slip  over  it  from  almost  any  position,  and  the 
bridge  can  be  dropped  in  place  very  easily. 

The  occlusal  edges  of  the  band  having  been  turned  in,  this  end  is 
filed  perfectly  flat  and  the  floor  of  No.  28-gauge  coin  gold  is  flattened 
in  the  swagging  device  and  sweated  to  it  in  the  same  manner  as 
already  described  in  the  making  of  the  cap  for  a  Richmond  crown 


RETAINING  ABUTMENTS 


231 


(Fig.  379).  The  extending  edges  of  the  floor  are  then  trimmed  flush 
with  the  band,  and  the  sides  of  the  cap  are  nicely  smoothed  with  a 
file  or  a  fine  disk  and  polished.  The  floor  of  the  cap  is  not  polished 
at  this  time,  the  reason  for  which  will  be  given  later. 

The  inside  of  the  cap  is  then  given  a  very  thin  coating  of  wax. 
After  the  wax  is  applied,  all  the  excess  that  can  be  removed  is 
scraped  away  with  the  spatula.  The  cap  is  next  grasped  with  pliers 
and  passed  quickly  through  the  Bunsen  flame  so  as  to  distribute  the 
little  remaining  wax  evenly,  leaving  only  a  very  thin  film.  If 
there  is  too  thick  a  coating  of  wax  on  the  inside  of  the  cap,  it  can 
easily  be  pulled  away  from  the  fusible  metal  stump,  or  it  will  be 
found  that  when  the  outer  band  is  driven  over,  the  wax  will  be 
squeezed  out  around  the  edges,  allowing  the  inner  band  to  buckle, 
with  the  result  that  the  work  will  have  to  be  done  over  again 
(Fig.  380). 


Fig.  381 


A  tube  of  paper  is  then  made,  or  a  piece  of  rubber  tubing  may  be 
used,  and  the  band  pushed  well  down  into  it  so  that  the  gingival 
edge  is  an  inch  or  more  below  the  upper  end  of  the  tube.  The 
paper  tube  should  fit  the  caj)  tightly,  and  is  hehl  in  place  with  a 
gum  band  or  piece  of  wire  (Fig.  3S1).  The  tube  is  now  filled  with 
fusible  metal  which  is  allowed  to  cool  thoroughly  before  renioving 
the  paper.  Fig.  3X2  shows  a  ladle  especially  adajited  for  fusible 
metal,  when  used  in  small  (piaiitities.  It  has  a  long,  narrow  lip, 
which  allows  of  the  riictal  being  poun-d  iiit(»  a  very  small  open- 
ing as  the  i>ai)cr  tubes  in  which  the  caps  are  placed.  The  ladle 
will  also  hold  enough  metal  to  p(;ur  a  large-si/ed  die  for  a  saddle. 


232  REMOVABLE  BRIDGE-WORK 

The  metal  used  for  this  purpose  should  have  a  very  low  fusing 
point.  Melotte's  metal,  or  any  of  the  metals  which  require  a 
higher  heat  than  the  boiling  point  of  water  to  melt,  are  not  suitable 
for  this  purpose.     The  metal  which  the  writer  has  found  most 


Fig.  382 

suitable  for  thus  reinforcing  the  caps  is  made  from  the  following 
formula  of  Dr.  CM.  Richmond,  which  was  published  many  years 
ago  in  one  of  the  dental  journals. 

Tin 20  parts. 

Lead 19      " 

Cadmium 13      " 

Bismuth 48      " 

100      " 

They  are  not  melted  in  the  order  of  their  fusibility,  but  in  the 
order  in  which  they  are  given,  as  the  metals  combine  better  if 
melted  in  this  manner.  A  new  crucible  should  be  used  for  the  pur- 
pose, or  one  which  has  been  used  only  for  the  making  of  the  metal. 
The  tin  is  placed  in  the  crucible  and  heated  until  it  is  entirely 
melted  and  as  soon  as  this  has  taken  place,  the  lead  is  dropped  in. 
When  this  has  also  melted,  the  cadmium  is  added  and  when  this 
too  has  melted,  the  crucible  should  be  taken  from  the  fire,  or  the 
fire  should  be  turned  out.  The  bismuth  is  then  added  in  pieces 
and  stirred  in  with  a  pine  stick  until  it  is  entirely  melted.  It  must 
not  be  forgotten  to  remove  the  crucible  from  the  fire  as  soon  as  the 
cadmium  has  disappeared.  If  this  is  not  done  before  adding  the 
bismuth,  the  fusing  point  of  the  mass  is  lowered  so  rapidly  that 
the  metal  will  burn  and  become  worthless  for  the  purpose  for 
which  it  is  intended. 

This  metal  fuses  at  about  160*^  F.  It  is  quite  hard  and  does  not 
shrink  at  all  on  cooling,  and  after  using,  it  can  readily  be  removed 
from  the  gold  cap  by  placing  it  in  hot  water. 

The  metal-filled  cap  having  become  quite,  cold,  the  paper  is 
removed  and  a  perfectly  solid  and  rigid  stump  results,  over  which 
it  is  possible  to  make  a  perfectly-fitting  outer  cap,  and  the  surplus 


RETAINING  ABUTMENTS 


233 


metal  extending  as  it  does  over  an  inch  or  more  beyond  the  cap, 
makes  a  con^•enient  handle  bv  which  to  hold  it  for  further  operations 
(Fig._3S3). 

It  is  well  to  emphasize  the  fact  that  the  band  should  be  thoroughly 
polished  before  filling  it  with  the  fusible  metal.  Being  reinforced, 
and  having  the  extending  stump  for  a  handle,  it  would  be  easier 
to  polish  and  finish  it  after  it  has  been  filled  with  the  metal,  but 
there  would  be  danger  of  future  trouble  should  this  be  done.  Should 
the  band  be  polished  at  this  time,  it  would  be  impossible  to  prevent 
the  polishing  wheels  from  coming  in  contact  with  the  fusible  metal. 
The  surface  of  the  gold  of  the  inner  cap  would  thus  become  con- 
taminated, so  that  in  fitting  the  outer  band  it  would  in  turn  become 
contaminated  from  the  film  of  the  base  metal  which  has  been 
brushed  over  the  inner  cap,  even  th'ough  it  could  not  be  seen,  and 
the  band,  at  the  first  annealing,  by  alloying  with  the  base  metals 
would  become  so  brittle  as  to  be  absolutely  worthless. 

It  cannot  be  too  strongly  impresse<:l  upon  the  reader,  the  danger 
of  the  precious  metals  becoming  contaminated  by  contact  with 
base  metals  on  the  work  bench.  The  greatest  care  should  be  used 
to  keep  them  from  unnecessary  contact.  Even  the  slightest  trace 
of  any  of  these  base  metals  or  alloys  will,  on  the  piece  being  heated, 
as  in  annealing  or  in  soldering,  entirely  destroy  the  working  qualities 
of  the  precious  metals,  so  that  they  are  good  for  nothing  until 
refined  and  remelted.  All  pieces  swaged  or  fitted  upon  base  metal 
dies  should  be  given  a  bath  in  nitric  acid  before 
annealing  or  soldering. 

The  bench  on  which  base  metal  has  been  used, 
and  the  instruments  which  may  have  been  used 
around  it,  should  be  thoroughly  cleansed  before 
again  coming  in  contact  with  gold  or  platinum. 

Making  the  Outer  Cap. — The  measurement  of  the 
inner  cap  is  taken  just  below  the  point  where  the 
occlusal  end  has  been  rounded  (Fig.  383,  aa),  and  the 
outer  band  cut  from  Xo.  30-gauge  coin  gold  on  an 
angle  of  the  same  degree,  or  even  slightly  greater 
than  was  the  inner  band  (Fig.  374).  This  is  then 
beveled  and  sweated  together  in  the  same  manner  as 
was  the  iimer  band,  and  afterward  the  lapped  joint 
is  hammered  over  the  beck-horn  of  an  anvil  or 
squeezed  between  the  jaws  of  the  stretching  pliers  until  the  seam  on 
the  inner  side  is  entirely  obliterated.     It  is  now  annealed  and  given 


Fio.  ^83 


234 


REMOVABLE  BRIDGE-WORK 


approximately  the  shape  of  the  stump,  and  the  inner  cap  is  driven 
into  it  by  placing  the  occlusal  end  of  the  band  on  the  anvil  and 


Fig.  384 


Fig.  385 


tapping  the  end  of  the  fusible  metal  stump  with  a  small  hammer, 
forcing  it  into  the  outer  band  which  is  thus  stretched  over  it,  as  in 
Fig.  384. 


RETAIN  I  Xa   ABUTMENTS 


231 


It  should  not  be  allowed  to  come  in  contact  with  the  fusible 
metal  except  in  such  cases  as  will  be  described  later.  The  band 
will  be  foimd  to  fit  the  inner  cap  so  tightly  as  to  render  it  immovable. 
This  may  be  remedied  by  using  a  heavy  steel  burnisher  (Fig.  385) 
and  burnishing  the  sides  of  the  band  as  it  fits  over  the  inner  cap. 
This  burnishing  will  stretch  it  very  slightly,  but  sufficient  to  allow 
of  it  being  removed  from  the  stump.  It  should  not  be  burnished 
so  as  to  make  it  loose,  but  just  enough  to  permit  of  it  being  forced 
ofJ  with  an  instrument. 

The  band  is  then  marked  and  carefully  trimmed  to  a  line  parallel 
with  the  gingival  edge  of  the  inner  band,  and  again  driven  on  until 
it  comes  to  within  a  little  less  than  one-sixteenth  of  an  inch  of  the 
gingival  edge  of  the  inner  cap  (Fig.  386).  The  occlusal  end  is  trimmed 
very  nearly  to  the  floor  of  the  inner  cap  and  then  pressed  in  all 
around  over  the  rounded  edge  of  the  inner  cap  so  that  it  fits  at  this 
point  closely  (Fig.  386).    This  can  be  done  with  the  face  of  a  flat 


Fig.  .387 


file  by  giving  it  a  rolling  motion,  laying  it  flat  on  the  side  of  the 
band  and  rolling  over  the  occlusal  end.  It  should  not  be  done  by 
burnishing  as  the  burnishing  would  stretch  the  metal  at  this  point 
and  make  it  impossible  to  obtain  an  accurate  fit. 

The  occlusal  end  is  then  filed  flush  with  the  floor  of  the  inner  cap. 
In  doing  this  and  in  making  it  i)crfectl\'  flat,  it  will  be  necessary  to 
Hie  away  some  of  the  floor  of  the  inner  cajj  and  it  was  for  this  reason 
that  the  floor  was  made  of  No.  28  gold  (Fig.  387).  We  now  have 
an  outer  telescoping  cap  which  fits  the  imier  perfectly,  atxl  there 
is  no  method  which  can   be  employed  which  will  give  so  perfect  a 


236  REMOVABLE  BRIDGE-WORK 

fit.  The  outer  band  is  then  removed  and  a  floor  of  No.  30  coin 
gold  is  sweated  to  it.  Up  to  this  point,  no  solder  has  been  used, 
so  that  in  any  subsequent  soldering  operations  tJiere  is  no  possi- 
bility of  any  solder  making  its  way  to  the  inside  of  the  cap  through 
the  seams,  and  thus  destroying  the  fit. 

The  edges  of  the  floor  are  then  trimmed  flush  on  the  buccal  and 
lingual  sides  of  the  cap,  leaving  it  extend  a  little  out  from  the  cap 
centrally  on  the  mesial  and  distal  sides,  as  in  Fig.  388,  to  assist 
in  giving  the  cap  a  normal  contour  at  these  points. 


Fig.  388  Fig.  389 

It  is  essential  that  the  contour  of  the  cap  or  crown  be  restored 
so  that  it  will  present  a  normal  appearance.  This  is  done  by  building 
it  out  mesially  and  distally  with  coin  gold.  Pieces  of  No.  28  gauge 
coin  gold  are  used,  being  cut  about  one-half  or  three-quarters  longer 
than  the  buccal  and  lingual  diameter  of  the  cap  and  shaped  approxi- 
mately as  in  the  drawing  (Fig.  389),  the  gingival  edge  following  the 
festoon  of  the  band  and  coming  to  within  about  one-thirty-second 
of  an  inch  of  this  edge  and  extending  about  one-thirty-second  to 
one-sixteenth  of  an  inch  above  the  occlusal  end. 

These  pieces  of  gold  are  called  the  contour  wings.  One  is  placed 
in  position  on  the  cap  about  one-thirty-second  of  an  inch  above  the 
gingival  edge,  the  other  side  resting  on  the  extended  floor  of  the 


Fig.  390  ,  Fig.  391  . 

outer  cap  (Fig.  390).  This  allows  only  the  lower  edge  to  touch  the 
band  and  it  prevents  the  solder  from  flowing  farther  up  on  the  cap 
than  intended.  If  the  floor  has  been  trimmed  close  to  the  band 
all  around,  the  same  result  can  be  obtained  by  giving  the  wing  a 
short  bend  close  to  the  gingival  edge  as  in  Fig.  391.  It  is  held 
in  position  with  a  pair  of  pliers  and  fluxed  with  liquid-flux^  between 

1  A  solution  of  borax  and  boracic  acid. 


RETAINING  ABUTMENTS 


237 


the  wing  and  the  cap.  It  is  then  held  over  the  flame  of  a  Bunsen 
burner,  drying  the  flux  and  thus  holding  the  wing  temporarily  in 
position. 

The  cap  is  then  placed  on  a  charcoal  block,  the  side  on  which  the 
wing  is  tacked  being  uppermost,  and  it  should  so  rest  that  the  wing 
is  nearly  level.  A  very  minute  piece  of  21-carat  solder,  no  larger 
than  a  quarter  of  the  size  of  a  pin  head  is  placed  on  the  lower  edge 
of  the  cap  in  contact  with  the  wing,  as  in  Fig.  392.  The  whole  is  now 
thoroughI>-  heated  up  until  the  solder  melts  and  the  wing  is  tacked 
to  the  band  with  this  small  piece  of  solder.  The  cap  is  then  cleansed 
in  acid  and  the  wing  on  the  opposite  side  is  attached  in  the  same 


Fig.  3!>2 


Fig.  :im 


Fig.  ;i!)4 


Fig.  8<»5 


manner.  The  cap  is  next  placed  on  the  stump  and  the  wings  are 
brought  into  shape  with  the  pliers  so  as  to  give  a  contour  to  the 
crown,  the  ends  being  trimmed  as  may  be  necessarv  to  give  this 
result  (Fig.  393).  The  fact  of  their  being  only  just  lightly  tacked  at 
the  gingival  edge  permits  them  to  be  adjusted  outward  or  inward 
or  in  any  way  desired  to  give  the  required  contour.  Fig.  394 
represents  an  upper  molar  with  the  wings  brought  in  proper  posi- 
tion and  Fig.  395,  a  lower  molar. 

When  the  wings  have  been  brought  into  shape,  the  spring  of  the 
metal  will  be  such  as  to  keep  the  edges  from  actual  contact  with  the 
band.  To  overcome  this,  it  is  necessary  to  amieal  them  while  held 
in  close  contact,  as  follows:  The  edge  of  the  contour  wing  is  grasped 
with  a  pair  of  pliers,  one  beak  being  inside  of  the  band,  and  the 
other  resting  on  the  edge  of  the  contour  wing,  holding  it  in  place. 
The  flame  of  the  blow-pipe  is  then  thrown  onto  the  wing,  bringing 


238  REMOVABLE  BRIDGE-WORK 

it  to  a  red  heat,  holding  it  in  the  pliers,  as  in  Fig.  396,  until  it  is 
cool.  This  will  bring  it  in  contact  with  the  band,  and  overcome 
the  spring  of  the  metal.  This  is  repeated  at  different  places  until 
all  points  of  the  wings  are  in  contact  with  the  band. 

The  cap  is  thoroughly  cleansed  in  acid  and  after  it  is  rinsed  and 
dried,  it  is  well  fluxed  between  the  wings  and  cap  and  also  around 
the  edges  and  buccally  and  lingually  between  the  two  wings.  It  is 
now  placed  on  a  charcoal  block  with  either  the  buccal  or  lingual 
sides  uppermost  and  a  large  piece  of  21 -carat  solder  placed  between 
the  ends  of  the  wings,  as  in  Fig.  397. 

The  whole  cap  is  then  thoroughly  heated  up  with  the  blow-pipe 
and  the  solder  drawn  in  between  the  wings  and  the  cap  and  along 
the  edges,  using  sufficient  solder  to  flush  it  well  between  the  edges 
of  the  wings  and  cap,  but  not  enough  to  more  than  partly  fill  in 
between  the  contour  and  the  band,  as  in  Fig.  398. 


Fig.  396  Fig.  397  Fig.  398 

The  cap  is  then  cleansed  again  and  soldered  on  the  opposite  side 
in  the  same  manner,  bringing  the  solder  flush  between  the  ends  of  the 
wings,  also  along  the  lower  edge  between  the  wings  and  the  band. 
It  is  then  cleansed  in  acid  and  the  extending  wings  cut  and  filed 
flush  with  the  floor  of  the  cap  (Fig.  398).  A  suitable  cusp  button 
is  selected,  a  pure  gold  matrix  made,  filled  flush  with  coin  gold  and 
the  under  surface  filed  perfectly  flat.  This  cusp  may  be  selected 
after  the  band  has  been  contoured,  or  it  may  be  selected  before  and 
the  contour  brought  out  to  correspond  with  the  cusp. 

The  edges  of  the  cusp  should  extend  slightly  beyond  the  contour. 
After  it  has  been  filed  perfectly  flat,  the  under  surface  is  fluxed 
as  well  as  the  floor  of  the  cap  at  the  point  of  contact  and  held  in  the 
flame  of  the  Bunsen  with  a  pair  of  pliers,  until  the  flux  has  dried, 
thus  tacking  the  cap  and  cusp  together.  The  cusp  and  cap  are  then 
wired  tightly  and  placed  on  the  charcoal  block,  as  in  Fig.  399. 

A  large  piece  of  20-carat  solder  is  placed  on  the  buccal  or  lingual 


RETAINING  ABUTMENTS 


239 


side  of  the  cap,  resting  on  the  extending  edges  of  the  cusp.  The 
flame  of  the  blow-pipe  is  directed  on  the  cusp  which  should  extend 
a  little  over  a  depression  in  the  block  so  as  to  allow  the  cusp,  which 


Fig.  .399 


is  \'ery  thick  and  heavy,  to  be  thoroughly  heated  up  first,  and  the 
solder  melted  (Fig.  399),  flowing  it  in  between  the  floor  of  the  cap 
and  cusp.  The  cap  can  then  be  placed  on  its  side,  as  in  Fig.  400. 
and  the  c-usp  first  heated  thoroughly  and  the  flame  then  passed  over 


Vui.  400 


the  u|jpcr  and  lower  edge.  Frcsii  solder  is  added  and  as  it  melts, 
it  can  be  drawn  through  from  one  side  to  the  other,  uniting  the 
cusp  and  the  caj)  firmly. 


240  REMOVABLE  BRIDGE-WORK 

The  solder  should  always  be  drawn  from  one  point  and  enough 
of  the  solder  should  be  used  to  be  certain  that  it  is  drawn  entirely 
through  and  filled  flush  all  around  the  edges  of  the  contour,  uniting 
the  cusp  thoroughly  at  all  points.  If  the  operator  were  to  start  at 
one  point  and  unite  it  there  and  then  turning  the  crown  and  uniting 
it  at  different  points  all  around  on  the  outside,  he  might  afterward 
find  that  it  was  perfectly  soldered  on  the  outside,  but  the  solder 
had  not  drawn  entirely  through  from  one  side  to  the  other,  and 
that  the  entire  floor  of  the  cap  was  not  united  to  the  cusp.  The 
possible  result  would  be  that  in  future  operations,  when  the  piece 
has  been  very  highly  heated,  that  the  floor  of  the  cap  at  the  point 
where  it  was  not  united  with  the  cusp  may  have  expanded  and 
bulged  inward  as  in  the  illustration  (Fig.  401),  leaving 
a  large  blister  at  this  point.  If  this  does  happen, 
the  cap  may  be  placed  on  a  block  and  the  bulged 
floor  driven  back  into  place  with  a  stick.  This  can  be 
Fig.  401  accomplished  so  that  very  little  or  no  harm  will  result, 
but  the  appearance  of  the  cap  on  the  inside  is  spoiled. 
After  the  cusp  has  been  soldered,  the  extending  edges  are  ground 
off  flush  with  the  contour  and  the  whole  crown  is  finished  and 
polished.  The  outward  appearance  of  the  crown  is  now  the  same 
as  an  ordinary  contoured  shell  crown,  but  at  the  same  time,  it 
fits  the  inner  cap  perfectly. 

After  the  telescope  crown  has  been  completed,  the  inner  cap  is 
removed  from  the  fusible  metal  stump  by  immersing  it  in  boiling 
water.  The  cap  is  grasped  in  a  pair  of  pliers  and  as  the  metal 
softens,  the  cap  is  lifted  from  the  water  and  any  metal  remaining 
in  it  is  shaken  out  while  it  is  still  hot. 

The  cap  is  then  thoroughly  dried  and  placed  in  chloroform  to 
dissolve  any  wax  which  may  remain  on  the  inner  surface  of  the  crown 
after  which  it  is  placed  in  nitric  acid  and  left  for  a  time,  or  else 
boiled  in  the  acid  in  a  test  tube,  so  as  to  remove  any  traces  of  the 
fusible  metal,  as  the  slightest  trace  of  this  metal  left  in  the  cap 
would,  should  it  be  reheated,  render  it  brittle  and  worthless. 

Casting  Cusps  and  Contour. — It  is  well  to  say  a  word  at  this  point 
in  regard  to  casting  the  cusp  and  contour  on  the  telescope  caps. 
It  has  been  advocated  by  some,  that  the  outer  cap  be  made  in  the 
manner  described,  up  to  putting  on  of  the  contour,  and  the  cusp 
and  contour  be  then  molded  in  wax.  This  is  then  invested  and 
cast  in  the  customary  way.  A  telescope  crown  made  in  this  manner 
will  not  fit  the  inner  cap.    The  contraction  of  the  metal  is  such  that 


TELESCOPE   CRO]VX   AM)    TUBE   AM)  SPLIT   PIX        241 

the  outer  cap  will  become  too  small,  and  it  will  be  necessary  to 
grind  it  on  the  inside  in  order  to  make  it  go  over  the  inner  cap, 
thus  destroying  the  fit,  and  defeating  the  object  to  be  attanied, 
an  accurately  fitting  telescope  crown,  besifle  making  the  crown 
unnecessarily  heavy. 

The  contours  of  the  telescope  crowns  are  always  mesially  and 
distally,  except  where  the  teeth  are  in  an  abnormal  position.  A 
molar  or  a  bicuspid  may  be  turned  one-quarter  around.  Then  the 
contour  would  be  placed  buccally  and  lingually,  as  the  tooth  stands 
in  the  arch,  but  at  the  same  time  it  would  really  be  on  the  mesial 
and  distal  sides  of  the  tooth,  as  in  the  illustration.  Fig.  402  shows 
a  rotated  molar  and  Fig.  403,  a  bicuspid. 


Fig.  402  Fig.  403 

As  previously  stated,  the  telescope  crowns  should  be  used  in 
the  posterior  part  of  the  mouth  only,  and  never,  under  any  cir- 
cumstances, anterior  to  the  bicuspids. 

THE  TELESCOPE  CROWN  IN  COMBINATION  WITH  THE 
TUBE  AND  SPLIT  PIN. 

.  This  crown  is  indicated  where  there  is  but  a  single  retaining 
abutment  for  a  bridge,  or  where  there  are  two  retaining  abut- 
ments, but  the  crowns  are  so  very  short  that  it  will  be  impossible 
to  get  sufficient  hold  witli  a  simple  telescope  crown.  It  is  nearly 
always  indicated  in  the  lower  third  molar,  and  very  fre(iuently  in 
the  second  lower  molar. 

As  is  usually  the  case  with  the  lower  third  molars,  the  crown  is 
very  sliort,  and  at  times  (mi  the  distal  side,  it  is  necessary  to  cut  the 
stumj>  nearly  Hush  witii  the  gum,  or  even  beneatii  it,  in  onk'r  to 
place  a  cusp  thick  enough  to  give  strength  and  support  to  the  body 
of  the  briflge  which  is  to  Ik;  coimected  with  it. 

It  is  also  fn-cpieiitly  indicated  in  the  uj)i)cr  mohirs,  and  at  times 
ill  the  lower  bicusj)ids,  but  very  rarely  for  th<'  uj)|)er  bicuspids. 

The  Construction  of  the  Telescope  Crown  with  the  Tube  and  Split 
Pin.  The  iiiiKT  baud  is  iiiadc  and  fitted  to  the  stumjj  in  exactly 
16 


242  REMOVABLE  BRIDGE-WORK 

the  same  manner  as  for  the  ordinary  telescope  crown.  If  the  crown 
of  the  tooth  is  of  sufficient  length  so  that  the  depth  of  the  pulp 
chamber,  from  the  floor  to  thp  occlusal  end  of  the  stump,  is  in  the 
neighborhood  of  three-sixteenths  to  one-quarter  of  an  inch,  it  is  not 
necessary  that  the  tube  should  go  in  deeper  than  to  the  pulp  chamber 
floor.  If,  however,  the  crown  is  very  short,  it  may  be  necessary 
to  drop  the  tube  for  a  little  distance  into  one  of  the  roots.  In  the 
lower  molar,  it  is  generally  advisable  to  utilize  the  mesial  root  for 
this  purpose,  as  the  position  of  these  teeth  is  frequently  such,  that 
the  mesial  root  stands  at  a  better  angle  to  receive  the  tube,  as  in 
Fig.  404.  It  is  only  necessary  to  drop  the  tube  for  a  very  short 
distance  into  this  root,  and  as  a  general  rule,  owing  to  the  lingual 
inclination  of  the  tooth,  it  would  be  placed  toward  the  lingual  side. 


Fig.  404  Fig.  405 

In  the  upper  molars,  the  palatal  root  is  the  best,  as  it  is  of  a 
greater  size  than  are  the  others.  The  band  is  placed  in  position 
and  a  heavy  wire,  of  a  slightly  greater  diameter  than  the  tube 
which  is  to  be  used,  should  be  placed  in  the  pulp  chamber  or  the 
enlarged  canal,  resting  on  the  bottom,  and  held  lightly  in  position 
with  some  soft  wax  and  bent  so  as  to  clear  the  bite,  as  in  Fig.  405. 

The  impression  and  articulation  are  then  taken.  When  the 
impression  has  been  obtained,  the  pin  and  band  will  often  come 
away  with  the  impression.  Should  they  not  do  so,  they  can  be 
removed  and  replaced  in  the  impression,  after  which  they  are 
properly  waxed  in  place  and  the  sides  of  the  pin  lightly  covered 
with  wax.  The  impression  is  then  varnished  and  the  model  is 
made  and  separated  in  the  usual  manner,  the  band  and  pin 
removed  and  the  model  dried. 

The  edges  of  the  occusal  end  of  the  band  are  turned  in  slightly, 
the  same  as  in  the  regular  telescope,  and  a  floor  of  No.  28-coin  gold 
is  sweated  to  it,  and  the  excess  gold  of  the  floor  trimmed  away. 
By  observing  the  hole  in  the  stump,  where  the  heavy  wire  has  been 
removed,  it  can  be  ascertained  about  where  the  hole  should  be 
drilled  in  the  floor  of  the  cap  for  the  reception  of  the  tube.    The 


TELESCOPE  CROWN  AND  TUBE  AND  SPLIT  PIN       243 


hole  in  the  floor  should  be  made  of  a  diameter  about  one-half  greater 
than  the  diameter  of  the  tube  which  is  to  be  used  (Fig.  40(j).  The 
tube,  with  the  mandrel  inserted,  is  then  placed  through 
the  opening,  in  the  floor  of  the  cap  while  the  cap  is  on 
the  model,  the  lower  end  resting  on  the  floor  of  the 
pulp  chamber  or  on  the  bottom  of  the  cavity  made 
to  receive  it,  and  adjusted  so  that  it  will  be  parallel 
with  the  anterior  abutment  (Fig.  407). 

The  tube  must  also  be  adjusted  so  that  the  outer  cap,  when  the 
crown  is  finished,  with  the  pin  in  position,  will  draw  freely  from 


Fig.  406 


Fig.  407 


the  inner  cap.  This  should  be  tested  carefully  while  the  tube  is 
waxed  in  position,  before  investing  and  soldering.  This  may  be 
done  by  leaving  the  mandrel  in  the  tube  and  testing  it  from  all 
sides  with  a  flat  instrument  or  a  small  straight  edge  ])laced  against 
the  .sides  of  the  band,  as  .shown  in  the  illustration  (Fig.  40,S).  The 
cap  being  slightly  conical,  it  is  not  necessary  that  the  tube  be 
l)erfectly  parallel  with  the  sides  of  the  band  at  any  point,  but  it 
mu.st  be  in  such  a  ])osition  that  it  will  draw  freely. 

By  placing  the  edge  of  a  flat  file  on  the  side  of  the  l)an(l  on  a  line 
with  the  mandrel,  if,  as  the  mandrel  and  file  leave  the  band,  they 
are  i>arallel  or  converge  toward  the  upper  end  from  all  sides,  it  will 
be  known  that  the  outer  cap  will  pass  over  freely  after  the  pin 
has  been  soldered  to  it  (Fig.  40S).  On  the  contrary,  if,  as  the  man- 
drel and  file  leave  the  band,  they  dixcrge,  as  in  the  illustration, 
it  can  readily  be  seen  that  it  will  be  inipo.ssible  to  make  an  outer 
band  which  will  fit  the  irnier  band  aeenrately  and  have  it  draw  with 
the  pin  of  the  outer  cap  in  place,  as  shown  in  Fig.  409. 


244 


REMOVABLE  BRIDGE-WORK 


As  stated  above,  the  diameter  of  the  hole  in  the  floor  of  the  cap 
should  be  considerably  larger  than  the  outside  diameter  of  the 
tube  to  permit,  when  the  tube  is  soldered  in  place,  of  countersinking 


Fig.  408 


Fig.  409 


it  well  at  the  entrance,  so  that  the  pin  may  readily  find  the  open- 
ing. The  tube  should  be  in  the  center  of  the  opening  and  the  wax 
flowed  around  it  to  a  depth  of  about  one-thirty-second  to  one- 
sixteenth  of  an  inch  beneath  the  floor. 

The  wax  is  then  chilled,  the  mandrel  removed  from  the  tube, 
and  the  cap  invested,  care  being  taken  to  have  the  inside  perfectly 
filled  with  investment,  and  it  is  then  ready  for  soldering  (Fig. 
410). 

The  invested  piece  is  then  warmed  slightly  and  the  wax  removed, 
after  which  it  is  thoroughly  dried  out  and  heated  to  redness  and  the 
tube  soldered  in  place  with  20-carat  solder.  This  is  best  done  by 
using  the  solder  in  a  strip,  having  first  fluxed  the  tube  and  edges 
of  the  floor  at  the  opening. 

The  solder  is  held  as  shown  in  the  illustration,  and  as  the  flame 
of  the  blow-pipe  melts  it,  it  is  pushed  through  the  opening  around 


TELESCOPE  CROWN  AND   TUBE  AND  SPLIT  PIN       245 

the  tube  to  the  under  side  of  the  floor,  fillhig  the  space  which  has 
been  left  by  the  melted  wax  (Fig.  41 1).  After  it  has  been  soldered, 
it  is  removed  from  the  investment,  cleansed  in  acid  and  dried. 


Fig.  410 


Fig.  411 


The  tube  should  be  thoroughly  dried  out  before  cutting  off  the 
excess,  as  should  moisture  be  left  in  it;  the  filings,  working  into 
the  tube,  will  form  a  sort  of  paste  which  is  difficult  to  remove, 
while  if  it  is  perfectly  dry,  the  filings  can  be  readily  shaken  out, 
with  the  saving  of  quite  a  little  time. 

The  cap  is  then  smoothed  and  polished,  waxed  lightly  on  the 
inside  and  filled  with  fusible  metal,  the  same  as  for  the  regular 
telescope. 

The  measurement  is  taken  and  the  outer  band  made.  In  a  case 
of  this  character,  where  the  crown  is  very  short,  it  will  probably 
be  necessary  to  carry  the  oiiter  band  <h)wn  over  the  fusible  metal 
stump,  for  the  time  being,  in  order  to  s'ecure  a  fit  and  a  hold  on  the 
inner  cap  sufficient  to  allow  of  the  turning  in  and  filing  of  the 
occlusal  end  of  the  band  to  conform  with  the  inner  cap,  as  shown 
in  the  illustration  (Fig.  412). 

'I'he  edges  having  been  turned  in  at  the  occlusal  end  to  conform 
to  the  rounih'd  corners  of  tlie  iruier  cap,  it  is  filed  flush  with  the 
floor  of  the  irmer  caj),  enough  of  the  floor  being  filed  oil  to  make 
it  perfectly  flat  and  smooth  on  the  surface.  The  outer  band  is 
now  removed  and  cleansed  in  nitric  acid.  T^nless  this  be  carefully 
ol)servcd  trouble-  will  surely  foll(»w.    The  gingival  i-nd  is  sliortencd 


246 


REMOVABLE  BRIDGE-WORK 


and  festooned  to  follow  the  edge  of  the  inner  cap,  but  from  one- 
thirty-second  to  one-sixteenth  of  an  inch  shorter  (Fig.  413),  and  a 
floor  of  No.  30  coin  gold  is  sweated  to  it. 


Fig.  412 


Fig.  413 


In  the  making  of  a  telescope  crown  it  should  be  remembered 
that  after  the  outer  band  has  been  filed  flush  with  the  floor  of  the 
inner  cap  and  removed,  it  should  always  be  wiped 
out  thoroughly  on  the  inside  before  sweating  the 
floor  to  it.  If  this  precaution  is  omitted  or  if  any  of 
the  filings  or  dust  should  adhere  to  the  inside  of  the 
band,  they  will  become  sweated  to  the  sides  during  the 
process  of  uniting  it  to  the  floor.  This  would  render 
the  inside  of  the  band  rough,  and  would  result  in  the 
scratching  of  the  inner  band  when  the  outer  cap  is 
being  removed  or  replaced. 

The  floor  of  the  cap  is  trimmed,  as  in  the  case 
of  the  regular  telescope  crown,  being  made  flush  on 
the  buccal  and  lingual  sides  and  extending  slightly 
beyond  the  band  mesially  and  distally.  The  band 
is  then  contoured  with  wings  and  solder  in  the 
same  manner  as  in  the  making  of  a  regular  telescope 
crown. 

The  opening  in  which  to  place  the  split  pin  should 

now  be  located.     The  floor  of  the  inner  cap  having 

been  filed  perfectly  flat  and  smooth,  the  inner  edges  of 

the  tube  are  sharp  and  clear,  like  the  edges  of  a  steel 

Fig.  414         die.     The  outer  cap  is  placed  over  the  inner  cap,  and 


TELESCOPE  CROWN  AND  TUBE  AND  SPLIT  PIN       247 

the  floor  of  the  outer  cap,  at  the  point  over  the  entrance  to  the  tube, 
is  placed  on  the  end  of  a  soft  pine  stick  and  the  fusilile  metal  stump 
struck  a  sharp  blow  (Fig.  414),  indenting  the  floor  into  the  tube 
and  leaving  on  the  inside  a  clear  sharp  outline  of  the  opening 
(Fig.  415).  _ 

The  next  operation  is  to  countersink  the  tube  and  tit  the  pin  to  it. 
The  split  pin  should  tit  in  the  floor  of  the  outer  cap  tightly,  so  that 
no  excess  of  solder  can  pass  through  to  the  inner  side  of  the  cap; 
in  this  it  is  not  like  the  tube  in  the  inner  cap  which  fits  loosely. 


Fig.  415 


Fig.  416 


Fig.  417 


Fig.  418 


RJ3 


Fig.  419 


It  is  advisable  here  to  emphasize  a  most  important  point  which 
applies  in  all  cases  where  tubes  are  used.  It  is  well  known  that 
a  molten  mass  of  metal  contracts  on  cooling.  Thus  the  placing 
of  a  large  amount  of  solder  around  the  tube  results  in  its  contraction. 
It  is  evident  that  if  the  pin  were  made  to  fit  the  tube,  without  first 
enlarging  it  at  the  opening,  it  would  touch  only  at  the  point  where 
it  had  been  soldered,  leaving  the  lower  end  free  in  the  tube. 

For  the  sake  of  illustration,  these  conditions  have  been  somewhat 
exaggerated  in  the  enlarged  drawing  (Fig.  416).  It  will  be  observed 
that  the  contraction  of  the  metal  around  the  tube  has  drawn  it 
in  so  as  to  give  it  a  neck  smaller  than  the  body  of  the  tube.  It 
will  be  noticed  that  the  only  point  of  contact  of  the  pin  with  the 
tube  is  at  the  neck  (Fig.  417)  so  that  the  entrance  must  be  enlarged 
at  the  opening  in  each  case  sufficient  to  allow  the  mandrel  over 
which  the  tube  has  been  made  to  enter  freely.  This  is  best  done 
with  a  flame-shaped  finishing  bur  (Fig.  418).  After  the  neck  has 
been  enlarged,  the  entrance  to  the  tube  is  countersunk  and 
smoothed  in  order  that  the  pin  may  readily  find  the  opening  (Fig. 
419).  It  should  be  remembered  that  this  is  not  to  be  done  until 
after  the  location  of  the  entrance  to  the  tube  has  been  marked 
in  the  floor  of  the  outer  cap.  The  pin  is  then  made  to  fit  the  tube 
and  it  should  fit  easily,  but  not  loosely,  or  in  other  words,  it  should 
fit.    \  pin  which  fits  a  tube  loosely  does  not  fit  at  ah. 


248 


REMOVABLE  BRIDGE-WORK 


The  hole  in  the  floor  of  the  outer  cap  should  now  be  made,  the 
marking  on  the  inside  giving  the  position.  It  should  be  enlarged 
with  the  outer  cap  in  position  on  the  inner  cap,  just  enough  to 
allow  the  pin  to  pass  through  it  and  fit  the  hole  in  the  floor  of  the 
outer  cap  tightly. 

The  selected  cusp  having  been  filled  and  filed  perfectly  flat  on 
the  under  surface,  is  then  placed  in  position  on  the  outer  cap,  the 
pin  for  the  time  being  having  been  removed.  The  under  surface  of 
the  cusp  is  marked  through  the  opening  in  the  floor  which  was 
made  for  the  pin  (Fig.  420). 


FiCx.  420 


Fig.  421 


The  cusp  is  then  removed,  the  pin  replaced  in  the  tube  through 
the  floor  of  the  outer  cap,  with  the  split  of  the  pin  running  buccally 
and  linguall3^  The  pin  is  waxed  firmly  in  position,  chilled,  and  the 
outer  cap  with  the  pin  in  place  is  removed  from  the  inner  cap  and 
invested  (Fig.  421).  The  inside  of  the  cap  should  be  moistened 
before  filling  with  investment,  so  that  the  operator  may  be  certain 
that  it  is  perfectly  filled  and  that  there  are  no  air  bubbles,  or  any 
unfilled  space  around  the  pin  on  the  inside  of  the  cap,  which  would 
allow  any  of  the  solder  to  pass  beneath  the  floor.  It  should  then 
be  heated-up  and  soldered  with  21 -carat  solder,  a  very  small  piece 
being  used  for  the  purpose.  The  flame  is  first  thrown  on  the  split 
pin,  as  it  is  much  heavier  than  the  floor  of  the  cap,  until  it  is  well 
heated.  The  flame  is  then  lowered  to  the  floor  of  the  cap,  drawing 
the  solder  around  the  pin  and  uniting  it  perfectly  (Fig.  421). 

A  hole  should  then  be  drilled  through  the  cusp  at  the  point 
marked  through  the  opening  in  the  floor  of  the  cap  and  enlarged 
sufficiently  to  allow  it  to  readily  pass  over  the  pin  extending  through 
the  floor,  leaving  space  on  all  sides,  as  in  Fig.  422.  The  pin  should 
be  cut  off  close  to  the  floor  so  that  when  the  cusp  is  soldered  to  the 
cap,  the  pin  will  be  entirely  covered  with  solder.     The  pin  should 


TELESCOPE  CROWX  AND   TUBE  AXD  SPUT   PfX 


240 


not  extend  abo^•e  the  cusp  so  that  it  may  be  seen,  as  the  color 
of  this  metal  being  much  hghter  than  the  cusps,  if  it  is  not  covered 
with  solder  will  show  and  sj)oil  the  appearance  of  the  occlusal 
surface  of  the  crown. 


Fig.  422 


Fig.  42.3 


Fig.  424 


The  cap  is  invested,  care  being  taken  to  fill  it  perfectly  on  the 
inside.  The  investment  should  extend  about  half  way  to  the  occlusal 
surface  on  the  outside.  The  investment  is  now  thoroughly  dried 
and  the  floor  of  the  cap  and  the  under  side  of  the  cusp  is  well  fluxed 
and  the  cusp  is  placed  in  position.  It  is  then  thoroughly  heated 
and  soldered  with  21 -carat  solder,  the  .solder  being  used  in  a  strip, 
the  end  of  the  strip  being  placed  in  the  opening  through  the  cusp 
over  the  pin  (Fig.  428).  As  the  solder  melts,  the  strip  is  pressed 
into  the  oi)ening  until  it  is  drawn  through  from  this  point  to  all 
sides  of  the  crown,  and  also  filling  the  opening  and  covering  the 
pin  fFig.  424).  This  is  also  an  excellent  way  of  uniting  the  cusp 
to  the  outer  cap  in  an  ordinary  telescope  crown,  making  a  smaller 
hole  in  the  center  of  the  cusp,  then  wiring  it  in  place  and  investing 
and  drawing  the  solder  to  all  parts  through  the  hole  in  the  center 
of  the  cusp.  Soldered  in  this  way  there  is  little  likelihood  of  there 
being  any  point  between  the  floor  and  the  cus])  which  is  not  ])crfectly 
united. 

The  crown  is  now  removed  from  the  investment,  cleansed  in  acid 
and  finished  in  the  .same  maimer  as  the  regular  telescope  crown. 
If,  on  carving  the  cusps,  it  is  found  that  the  pin  shows  through  the 
solder,  it  can  be  ground  away  with  a  bur  or  small  stone  and  then 
covered  again  with  a  small  amount  of  solder. 

The  imiercap  is  then  removed  from  the  fMsiblc  nictnl  stnuij)  and 


250  REMOVABLE  BRIDGE-WORK 

thoroughly  cleansed  with  chloroform  and  nitric  acid.  It  must  be 
remembered  that  the  cap  must  not  be  put  in  the  flame  or  reheated 
again,  until  it  is  certain  that  every  trace  of  the  fusible  metal  has 
been  removed. 

THE  KEY  AND  SHOE  ATTACHMENT. 

Another  stvle  of  anchorage,  especially  adapted  to  bicuspids 
and  molars  having  long  crowns,  is  the  dovetailed  key  and  shoe 
attachment. 

The  key  is  made  of  iridio-platinum  and  filed  smooth  to  form  a 
dovetail,  as  in  Fig.  425,  A  and  B. 


Fig.  425  Fig.  426  Fig.  427  Fig.  428 

A  strip  of  the  iridio-platinum.  No.  32  gauge,  is  bent  to  fit  the 
sides  of  the  key  perfectly  and  filed  off  flush  with  the  face  or  broad 
side  of  the  key,  and  a  floor  of  the  same  metal  fitted  to  it  and 
soldered  with  a  little  pure  gold  (Fig.  426,  A  and  B). 

In  using  this  form  of  abutment,  the  side  of  the  crown  to  which 
the  key  is  to  be  attached  should  be  straight  from  the  gum  line  to 
the  top  of  the  cusp  and  should  be  reinforced  with  a  piece  of  No. 
28-gauge  coin  gold  soldered  across  the  whole  face  of  the  crown 
with  21  carat  solder  and  polished  (Figs.  427  and  428). 

The  key  is  then  put  in  place,  a  hole  drilled  through  it  and  the 
side  of  the  band  to  which  it  is  attached  with  a  small  platinum 
rivet,  such  as  a  tooth  pin  (Fig.  429,  A,B),  the  under  surface  of  the 


Fig.  429  Fig.  430  Fig.  431 

key  having  first  been  covered  with  pure  gold,  as  the  union  between 
iridioplatinum  and  the  solder  is  not  strong.  The  key  may  then 
be  tuned  a  little  to  the  right  or  left,  revolving  it  on  the  rivet 
(Fig.  430)  to  make  it  parallel  with  the  other  abutment. 


REMOVABLE  ATTACHMENT  FOR  ANTERIOR  TEETH     251 

After  it  litis  IxH'H  iuljiisti'd,  it  is  soIcUtccI  to  the  Cii]),  usiiiu'  a  small 
amount  20  carat  solder  which  is  ))lacc<l  on  the  lower  end  of  the  key 
next  to  the  band  at  point  r,  Fig.  429,  .1,  and  from  there  drawn  to 
the  upper  end  of  the  key,  uniting  it  firmly  to  the  face  of  the  crown. 

The  female  part  of  the  attachment,  or  the  shoe,  is  then  slipped 
over  the  key  and  a  thin  piece  of  platinum  plate  cut  out  to  slip  down 
over  it  next  to  the  crowai  (Fig.  431),  and  this  is  burnished  closely 
to  it.  It  is  then  waxed  to  the  shoe,  removed,  invested,  and  covered 
with  pure  or  coin  gold,  uniting  it  to  the  shoe  and  filling  the  sides 
flush,  as  in  Fig.  432.  After  having  been  cleansed,  it  is  trimmed 
to  its  proper  dimensions,  and  replaced  on  the  crowai.  The  facings 
are  now  ground  in  and  the  bridge  constructed.  The  shoe  being 
soldered  into  the  end  of  the  body  of  the  bridge  as  in  Fig.  433. 


/^^^^^ 


Fig.  432  • 

If  a  saddle  is  to  be  used,  the  plate  facing  the  crown,  with  the 
shoe  attached,  is  carefully  fitted  to  the  saddle.  The  saddle  is  then 
waxed  firmly  to  it,  imbedding  a  piece  of  inm  or  brass  wire  in  the 
wax  along  the  shoe  and  saddle  to  stifl'en  it  and  prevent  distortion 
while  removing  it  from  the  key  and  crown,  invested  and  soldered 
with  21 -carat  solder. 

The  necessary  trimming  and  fitting  is  now  done  and  it  is  replaced 
on  the  model  and  the  bridge  constructed,  as  will  \)v  described  in 
Chapter  on  Saddle  Bridges. 

REMOVABLE  ATTACHMENT  FOR  THE  ANTERIOR  TEETH. 

These  atttachments  are  designed  for  the  teeth  anterior  to  molars, 
where  it  is  undesirable  that  any  gold  should  be  seen.  The  cap  is 
made  practically  the  same  as  for  a  Fvichmond  crown,  the  stump  being 
left  standing  out  of  the  gum  until  after  the  tooth  has  been  trinuned 
and  the  band  fitted. 

In  fitting  the  band  to  the  root,  care  should  be  taken  to  have  it 
nearly  i)arallel  with  the  long  axis  of  the  tooth,  as  in  Fig.  434,  and 
any  excessive  incliiiation  in  aii,\-  direction  as  in  I''ig.  h')')  should  be 
avoided. 


252  REMOVABLE  BRIDGE-WORK 

After  the  band  has  been  fitted,  the  stump  is  faced  in  the  same 
manner  as  for  a  Richmond  crown,  except  that  it  should  not  be  cut 
quite  as  far  under  the  gum  labially,  for  the  following  reason.     In 


Fig.  434  Fig.  435 

a  Richmond  crown,  the  band  should  be  from  one- thirty-second 
to  one-sixteenth  of  an  inch  beneath  the  gum  on  the  labial  side 
(Fig.  436),  so  that  the  band  will  be  entirely  hidden  for  a  number 
of  years.  If  the  same  procedure  be  followed  with  a  removable 
piece,  the  band  being  far  beneath  the  gum  line  allows  the  gum  to 
crowd  over  the  edge  of  the  cap  and  onto  the  floor  when  the  bridge 
is  removed,  so  that  when  the  bridge  is  replaced,  the  gum  would 
be  pinched  between  the  outer  and  inner  caps,  and  a  constant 
irritation  of  the  tissues  result. 


Fig.  437 

The  tooth  should  be  trimmed  from  one-sixty-fourth  to  one 
thirty-second  of  an  inch  below  the  gum  line  on  the  labial  side 
and  should  stand  about  the  same  distance  above  the  gum  line  on 
the  lingual  side  and  the  band  trimmed  flush  with  it.  The  placing 
of  the  floor  on  this  will  raise  it  high  enough  so  that  there  will  be 
little  liability  of  the  gum  coming  over  the  floor  sufficiently  to 
allow  of  its  being  pinched  between  the  outer  and  inner  caps  (Fig. 
437). 

The  canal  is  enlarged  with  reamers,  which  are  made  for  the 
purpose,  as  far  lingually  as  possible  for  the  reception  of  the  tube. 

The  band  is  then  faced  off  and  a  floor  of  No.  28-gauge  coin  gold 
sweated  to  it.  The  surplus  metal  is  trimmed  away  and  a  hole  made 
through  the  floor  to  allow  for  the  placing  of  the  tube  in  position. 


REMOVABLK  ATTACHMENT  FOR  ASTKRIOR   TEETH     23:5 

As  in  the  case  of  the  telescope  crown  with  tube  and  split  pin, 
the  hole  in  the  floor  of  the  cap  should  be  considerably  larger  than 
the  outside  diameter  of  the  tube,  so  as  to  allow  the  solder  to  run 
through  and  provide  for  countersinking  (Fig.  438).  The  cap  is 
then  placed  on  the  stump,  the  tube  placed  in  the  root  and  held 
in  position  while  it  is  being  thoroughly  waxed  (Fig.  439). 


Fu;.  4:is  Fit;-  439 


After  waxing,  the  cap  is  chilled  with  cold  air  or  ice-water  and 
removed  from  the  root  with  the  tube  in  position.  This  should 
be  tlone  by  passing  a  hooked  instrument  under  the  gum  and  oyer 
the  edge  of  the  band,  working  from  different  sides,  and  mo^•ing 
it  a  little  at  a  time,  so  as  not  to  change  the  position  of  the  tube  in 
the  cap.  It  should  be  noted  whether  the  wax  has  drawn  through 
to  the  under  side  of  the  floor  of  the  cap  on  all  sides  and  should  there 
be  any  point  at  which  it  has  not  done  so,  a  little  wax  may  be  added 
and  the  cap  again  tried  on  the  stump. 

The  cap  is  then  invested,  care  being  taken  to  have  the  inside 
of  the  cap  well  filled  with  the  investment,  and  soldered  with  20- 

carat  solder. 

The  same  care  should  be  exercised  in  placing  the  tube  through 
the  cap,  to  get  the  sides  of  the  tube  and  the  sides  of  the  cap  parallel 
or  so  that  the  outer  cap  will  draw,  as  in  the  case  of  the  telescope 
crown  with  the  tube.  The  correctness  of  the  inclination  of  the 
tube  .should  be  ascertained  by  i)lacing  a  flat  instrument  on  the 
lingual  side  of  the  cap  and  also  on  the  mesial  and  distal  sides, 
the  mandrel  being  left  in  the  tube  while  the  test  is  being  made. 
The  correct  relation  of  the  tube  on  the  lingual  and  mesial  and  dis- 
tal sides  of  the  cap  is  shown  in  Figs.  440  and  441,  an.l  un<ler  no 
consideration  should  they  be  placed  in  the  position  indicated  m 
Figs.  442  and  443. 

If  after  the  tube  has  been  waxed  in  position  and  it  together 
with  the  cap  is  removed  fn.in  the  root,  a  condition  similar  to  that 
shown  in  Figs.  \V1  and  113  is  found,  it  should  be  n-plaeed  on  the 
root  to  see  if  the  relation  of  the  tube  and  a  cap  have  not  been  changed 


254 


REMOVABLE  BRIDGE-WORK 


in  remo\'ing  it  from  the  stump.  If  it  is  found  that  it  lias  not  changed, 
it  may  be  necessary  to  make  a  new  band  throughout,  tilting  it 
enough  in  one  direction  or  another  so  that  a  correct  relation  of  the 
tube  and  cap  can  be  obtained.  No  attention  need  be  given  to  the 
relation  of  the  tube  to  the  labial  side  of  the  cap,  as  the  half-band 
engages  only  the  lingual  half  of  the  inner  cap. 


Fig.  440 


Fig.  441 


Fig.  442 


Fig.  443 


After  soldering,  the  cap  is  removed  from  the  investment,  cleansed 
in  acid  and  finished.  The  cap  and  the  inside  of  the  tube  should 
be  thoroughly  dried  out  before  doing  any  filing  or  grinding.  The 
excess  metal  of  the  tube  is  cut  away,  the  floor  filed  perfectly  flat 
and  the  neck  of  the  tube  opened  so  that  the  mandrel  over  which 
it  has  been  made,  will  enter  freely,  after  which  it  is  countersunk, 
leaving  the  edges  of  the  opening  perfectly  smooth  (Fig.  444). 

Fitting  the  Pin  in  the  Floor  of  the  Outer  Cap.— The  pin  is  then 
fitted  to  the  tube.  The  floor  of  the  outer  cap  should  be  made  of 
No.  28  gauge  coin  gold.  A  piece  of  the  metal,  a  little  larger  than  the 
cap,  is  selected,  and  the  hole  drilled  through  it  at  an  angle  corre- 
sponding to  the  angle  of  the  floor  of  the  inner  cap  with  the  tube. 
The  pin  should  fit  tightly  into  this,  passing  through  the  floor  to  the 
bottom  of  the  tube,  care  being  taken  that  the  outer  floor  fits  closely 
down  to  the  floor  of  the  inner  cap  at  all  points.  The  pin  is  then 
waxed  to  the  floor  (Figs.  445  and  446). 


REMOVABLE  ATTACH MEXT  FOR  AXTERIOR   TEETH     2o5 

As  the  strain  on  any  bridge  is  always  buccally  and  lingually  or 
labially  and  lingually,  and  never  mesially  and  distally.  in  placing 
the  pin  in  the  cap,  the  split  should  always  extend  from  the  labial 
to  the  lingual  sides,  as  in  Fig.  447. 


t 


Fig.  444  Fig.  445  Fig.  446  Fig.  447  Fig.  44S 

Thus  strength  of  the  pin  is  far  greater  if  placed  with  the  split 
labially  and  lingually,  than  it  would  be  if  it  were  placed  mesially 
and  distally.  This  can  readily  be  demonstrated  with  a  strip  of  the 
half  round  wiTe,  of  which  the  pins  are  made  (Fig.  448).  It  will  be 
found  that  it  can  be  bent  very  easily  flatwise,  but  in  trying  to  bend 
it  edgewise,  it  will  be  very  stiff.  If  the  pin  were  placed  with  this 
split  mesially  and  distally  any  lateral  movement  would  have  a 
tendency  to  bend  the  pin  much  more  easily,  the  two  surfaces 
sliding  together,  but  by  having  the  strain  come  edgewise  on  the 
pieces,  far  more  than  double  the  strength  will  be  obtained  than  if 
it  were  placed  reversely. 

Investment  should  be  made  as  in  Fig.  449,  making  a  small  invest- 
ment corresponding  with  the  size  of  the  piece  to  be  soldered,  care 
being  taken  to  get  the  investment  thoroughly  around  the  pin  on 
the  under  side  of  the  floor  where  it  passes  through  it.  Very  little 
solder  should  be  used  to  connect  this,  the  solder  being  placed  at  the 
mesial  side  of  the  pin  in  contact  with  the  floor  (Fig.  449, «)  the  pin 
and  opening  in  the  floor  having  previously  been  fluxed.  It  is  then 
soldered  with  21 -carat  sfdder.  In  soldering,  the  investment  should 
be  first  thoroughly  heated-up  and  after  it  has  reached  a  red  heat,  a 
small  blue  flame  is  thrown  directly  on  to  the  i^in  which  is  so  much 
thicker  and  heavier  than  the  H(.(»r  that  it  requires  a  greater  length  of 
time  in  heating  up.  The  flame  is  held  «»ii  the  pin  until  the  melting 
point  of  the  solder  is  nearly  reachetl.  It  is  then  gradually  lowere<l 
to  the  point  of  junction  of  the  floor  and  pin  and  held  there  until 
the  solder  flows  entirely  around.  The  ca|)  is  then  rem(»ve«l  from  the 
investment,  cleansed  in  acid  and  dried. 


25G 


REM 0 VABLE  BRIDGE-  WORK 


The  pin  and  floor  are  now  placed  in  position  over  the  inner  cap 
and  the  floor  trimmed  just  flush,  and  paraUel  with  the  sides  of  the 
cap  (Fig.  450).  This  should  be  done  with  a  file  or  a  wheel,  and  care 
taken  not  to  trim  it  to  a  bevel,  as  in  Fig.  451,  but  to  leave  it  flush, 
as  in  Fig.  450,  otherwise  when  the  half-band  is  put  in  position  it 
could  not  be  brought  in  contact  with  the  floor  of  the  outer  cap. 


Fig.  449 


Fig.  450 


Fig.  451 


Making  a  HaK-band. — The  half-band  should  be  made  of  the  same 
material  and  gauge  as  the  floor  of  the  cap,  No.  28.  It  should  not 
come  farther  labially  than  the  labial  side  of  the  pin  and  should 
extend  a  little  above  the  floor  of  the  outer  cap  and  down  nearly 
to  the  lower  edge  of  the  inner  cap  (F'ig.  452).  It  should  be  bent 
and  fitted  carefully  so  that  it  is  in  contact  with  the  floor  at  all 
points,  and  when  waxed  tightly  to  the  floor  of  the  cap,  removed 
for  investment.  The  piece  should  first  be  moistened  on  the  under 
side  so  that  the  investment  may  fill  it  thoroughly,  as  it  is  neces- 
sary that  the  corners  should  be  well  filled  so  as  to  prevent  any 
solder  from  flowing  through  at  this  point. 


Fig.  452 


Fig.  453 


On  the  lingual  and  mesial  and  distal  sides,  the  investment  should 
be  only  high  enough  to  engage  the  lower  edge  of  the  half-band  so 
as  to  hold  it  in  position,  as  in  Fig.  453.  It  is  desirable  to  have  the 
investment  far  enough  below  the  floor  of  the  cap  so  that  it  may  be 
thoroughly  heated  at  the  point  of  contact  between  the  half-band 
and  the  floor,  thus  allowing  of  its  being  more  easily  soldered.  The 
investment  is  then  dried  out  and  the  piece  fluxed  preparatory  to 
soldering. 


REMOVABLE  ATTACHMEXT  FOR  ANTERIOR  TEETH     257 

There  is  a  correct  way  ami  a  wrong  way  to  solder  the  half-band 
to  the  floor  of  the  cap.  In  the  correct  way,  the  solder  should  always 
be  placed  at  one  point  and  drawn  from  there  all  around  where 
it  is  necessary  to  unite  the  parts  (Fig.  454,  a).  If  two  pieces  of  solder 
are  placed  at  different  points,  as  in  Fig.  455,  a  a,  trouble  is  almost 
certain  to  result.  The  piece  is  heated-up  and  the  flame  flashed 
on  to  it,  melting  the  solder  at  these  two  points.  When  the  piece  is 
heated,  the  gold  will  expand,  and  in  the  half-band,  it  being  a  long 
and  narrow  strip  of  metal,  the  expansion  will  be  greater  than  it 
will  be  in  the  floor.     The  half-band,  being  united  to  the  floor  at 

a 


Fig.  454  Fig.  455  Fig.  456  Fig.' 457 

these  two  points,  as  in  the  illustration  (Fig.  456,  a  a),  when  the 
flame  is  thrown  on  the  lingual  side,  it  will  expand  lingually  and  be 
pushed  away  from  the  edge  of  the  floor  (Figs.  456  and  457),  with 
the  result  that  the  solder  is  drawn  down  through,  as  in  P'ig.  458, 
resulting  in  an  ill-fitting  band. 


Fig.  458  Fig.  459 

If  the  solder  is  placed  at  the  lingual  side  as  in  Fig.  452,  when  the 
piece  is  heated  from  that  side,  to  the  melting  point  of  the  solder, 
the  solder  draws  the  half-band  closely  in  contact  with  the  floor. 
The  metal  expands  as  in  the  other  case,  but  here  it  is  lield 
tightly  to  the  lingual  side  and  the  ends  of  the  (•xi)aiiding  half-band 
are  free  to  move  buccally  along  the  sides  of  the  floor.  By  first 
melting  solder  at  |)oint  a,  Fig.  454,  and  then  throwing  the  fiaine 
around  both  sides,  the  solder  is  drawn  to  the  sides  of  the  hiili'-biiiid, 
uniting  it  to  the  floor  perfectly.  It  is  then  removed  from  the  in- 
vestment and  cleansed  and  the  lower  edge  of  the  half-band  trinnned 
so  that  it  will  come  not  (|iiitc  in  contract  with  the  gum  (JMg.  15!)). 
The  outer  bands  of  crowns  of  this  t\pc  or  of  a  telescope  crown 
should  never  pass  beneath  the  ginn  margin. 
17 


258  REMOVABLE  BRIDGE-WORK 

PRECAUTIONARY  MEASURES  TO  PREVENT  BROKEN  FACINGS. 

The  making  of  the  outer  cap  for  this  form  of  attachment  requires 
the  greatest  care,  as  the  shghtest  deviation  in  technic  may  result 
later  in  great  annoyance  to  both  the  patient  and  dentist  through 
a  series  of  mishaps  in  the  way  of  broken  facings. 

In  almost  every  case  where  a  patient  presents  with  one  of  these 
facings  in  the  anterior  part  of  the  mouth  broken,  if  the  bridge  is 
removed  and  examined,  it  will  be  found  that  the  under  side  of  the 
floor  of  the  outer  cap  shows  a  very  small  polished  surface  jUst 
at  the  labial  side,  at  point  a  in  Fig.  460  and  Fig.  461.    This  shows 


Fig.  461  Fig.  462  Fig.  463 

that  it  was  bearing  heavily  at  the  place  so  marked  and  touching 
nowhere  else,  thus  bringing  the  entire  strain  of  the  force  exerted 
in  mastication  on  the  facing  at  this  point,  with  the  inevitable 
result  that  the  facing  is  broken,  as  there  is  no  porcelain  made  which 
will  withstand  such  a  strain  (Fig.  462). 

This  result  may  have  been  brought  about  by  a  slight  deviation 
in  the  technic  in  any  one  of  the  several  steps  taken  in  the  making 
of  the  outer  cap.  The  first  may  have  been  in  the  soldering  of  the 
pin  to  the  "floor.  In  soldering,  it  must  be  remembered  that  the 
tendency  of  the  molten  solder  is  to  flow  into  corners  and  angles,  or 
between  different  pieces  of  metal  which  may  be  nearly,  or  quite, 
in  contact  with  each  other.  In  the  drawings,  which  have  been 
purposely  somewhat  exaggerated  for  the  sake  of  illustration,  will 
be  found  the  explanation  of  the  causfe  of  the  larger  part  of  the 
trouble  from  broken  facings  in  the  anterior  part  of  the  mouth. 

In  Fig.  463  is  shown  the  floor  with  the  pin  in  position,  invested 
and  ready  for  soldering.  As  already  stated,  the  solder  is  placed 
on  the  labial  side  of  the  pin  and  resting  against  the  floor  at  point 
a,  Fig.  463.  If  a  large  amount  of  solder  has  been  used  at  this 
point,  what  is  the  result?  The  piece  is  highly  heated,  the  solder 
is  melted  and  naturally  seeks  the  smallest  space  in  which  to  lodge. 
It  is  thus  drawn  from  the  labial  to  the  lingual  side  of  the  pin, 


MEASURES   TO   PREVENT  BROKEN   FACINGS  259 

almost  the  entire  bulk  filling  in  the  narrow  angle  between  the 
floor  and  the  pin  (Fig.  4(33).  The  result  is  that  there  being  so 
great  a  bulk,  as  the  solder  cools,  it  contracts  quite  a  little,  chang- 
ing the  normal  plane  of  the  floor  {a  a,  Fig.  464),  drawing  it  up  on 
the  lingual  and  consequently-  depressing  it  on  the  labial  side  (Fig. 
4li4,  h  b),  with  the  re::ult  that  the  floor  will  touch  the  floor  of  the 
inner  cap  at  this  point,  the  labial  side,  and  at  no  other. 

It  can  readily  be  seen  what  the  result  would  be  if  it  were  allowed 
to  remain  in  this  condition,  and  the  facing  attached.  The  trouble 
would  have  been  obviated  in  the  first  place  if  only  just  enough 
solder  had  been  used  to  attach  the  pin  to  the  floor. 

The  second  step,  where  the  trouble  may  have  occurred,  is  in  the 
soldering  of  the  half-band  to  the  floor.  In  this,  as  in  the  previous 
case,  onl.\-  a  minute  portion  of  solder  should  be  used,  only  sufficient 
to  attach  the  half-band  to  the  floor. 

The  pin,  having  been  left  long  on  the  top  of  the  floor  and  sloping 
well  lingually,  may  come  nearly  or  quite  in  contact  with  the  upper 
edge  of  the  half-band.  If  a  large  amount  of  solder  is  used  in 
soldering  this  half-band,  the  solder  will  flow  in  between  the  pin 
(Fig.  465,  a),  and  the  floor  of  the  cap  and  in  cooling,  as  in  the 
first  step,  contracts  and  changes  the  plane  of  the  floor  (Fig.  466). 


Fig.  461  Vm.  405 


If  it  is  found  that  the  labial  side  of  the  floor  has  been  depressed, 
it  should  again  be  placed  on  the  inner  cap  and  the  floor  raised 
slightly,  so  as  to  be  clear,  Ix-fore  proceeding  with  the  next  opera- 
tion. 

The  same  thing  may  happen  in  the  final  soldering  if  the  pin  has 
been  long,  even  if,  in  the  previous  operations,  only  a  very  small 
amount  of  solder  has  been  used.  The  facings  having  been  backed 
and  the  piece  invested,  the  solder  may  bunch  up  and  cool  between 
the  pin  and  the  floor  and  so  produce  exactly  the  same  results  as  in 
the  previous  cases. 

The  cafj  being  comi)leted,  tlie  pin  should  be  cut  off  close  to  the 
floor  of  the  cap  before  grinding  the  facing  (Fig.  467).      If  this  is 


260  REMOVABLE  BRIDGE-WORK 

done  there  will  be  no  risk  of  trouble  happening  in  the  jfinal  soldering 
of  the  piece. 

It  should  be  remembered  that  the  whole  trouble  is  brought  about 
through  the  contraction  of  the  solder  on  cooling,  and  the  effect 


Fig.  467  Fig.  468 

of  this  should  be  carefully  studied,  not  only  in  this,  but  in  other 
operations,  as  it  is  something  that  will  have  to  be  contended  with 
in  all  of  our  prothetic  operations. 

It  is  better  that  the  floor  of  the  outer  cap  should  slightly  clear 
the  floor  of  the  inner  cap  at  the  labial  side,  rather  than  to  press 
heavily  on  it,  because  if  the  floors  are  not  in  actual  contact  at 
that  point  (Fig.  468),  there  will  be  little  probability  of  the  facing 
being  broken,  but  if  it  rests  heavily  there,  and  at  no  other  place, 
as  in  Fig.  462,  one  may  count  on  the  facings  being  broken  about 
as  fast  as  they  can  be  put  on. 

When  an  accident  of  this  kind  occurs,  and  the  floor  is  found  to 
press  heavily  on  the  labial  side,  the  bridge  should  be  placed  in  the 
mouth  and  the  outer  floor  lifted  slightly  off  from  the  inner  cap, 
so  that  it  will  clear  it  or  touch  it  but  very  lightly,  by  passing  a  thin 
instrument,  like  a  knife  blade,  between  the  two  floors  and  raising 
the  labial  side  of  the  outer  one  slightly.  If  this  is  done  when 
the  new  facing  has  been  replaced,  there  is  little  liability  of  its  being 
fractured. 

INLAY  ABUTMENTS. 

The  inlay  abutment  is  another  form  of  anchorage  which  is  useful 
for  small  bridges. 

These  attachments  are  especially  indicated  in  the  anterior  part 
of  the  mouth  where  but  a  single  tooth  is  to  be  replaced,  such 
as  a  missing  lateral  or  central,  or  a  lateral  and  central  incisor, 
both  on  the  same  side  of  the  mouth  and  at  times  even  where 
the  four  incisors  are  missing.  They  may  be  used  in  the  cuspids 
and  centrals.  In  the  back  of  the  mouth  they  are  frequently  indi- 
cated where  a  single  bicuspid  or  molar,  or  molar  and  bicuspid  is 


INLAY  ABUTMENTS  261 

missing,  or  at  times  even  the  two  bicuspids  and  molar.  An  inlay 
attachment  may  be  used  in  the  second  molar,  and  in  the  cuspid 
where  it  is  desired  to  preserve  the  crowns  of  these  teeth  for  esthetic 
reasons.  Frequently,  where  a  molar  crown  is  perfectly  sound, 
but  the  tooth  is  perhaps  somewhat  ill-shaped,  so  that  it  would 
be  almost  impossible  to  prepare  it  and  fit  a  band  properly,  it  is 
better  to  use  the  inlay  attachment. 

An  inlay  abutment  is  composed  of  an  inlay  through  which  a 
tube  is  passed  into  the  pulp  chamber  or  pulp  canal.  Afterward 
a  second  inlay  with  a  split  pin  attached  is  used  as  the  bridge 
attachment. 

In  using  these  anchorages,  it  is  always  necessary  to  devitalize 
the  teeth. 

Inlays  for  Anterior  Teeth. — In  the  making  of  these  attachments, 
those  for  the  anterior  part  of  the  mouth,  the  upper  centrals  or 
cuspids  will  first  be  considered,  all  of  the  low^r  incisors  being  too 
frail  for  such  an  anchorage. 

The  tooth  having  been  devitalized,  the  upper  third  of  the  canal 
is  carefully  filled  and  the  lingual  surface  of  the  crown  cut  away 
from  the  side  to  which  the  bridge  is  to  be  attached  to  about  two- 
thirds  of  the  distance  across  the  crown,  and  extending  down  to  the 
gingivae,  or  near  enough  to  it  so  that  there  will  be  room  to  allow 
of  sufficient  bulk  to  the  inlay  to  give  support  to  the  bridge  and 
at  the  same  time  aft'ord  a  good  occlusion  (Fig.  4()9). 

The  cavity  is  shaped  somewhat  as  shown  in  the  illustrations  (Figs. 
469  and  470),  being  made  non-retentive,  and  the  enamel  edges  of  the 


Fig.  409  Fi«-  470 

cavity  should  be  beveled  so  as  to  give  more  perfect  margins.  The 
canal'  is  then  enlarged  for  the  reception  of  the  tube.  It  should 
be  noted  that  4  larger  tube  can  be  used  in  an  inlay  abutment  than 
could  be  used  where  the  tooth  is  cut  })eneath  the  gum  labially, 
as  when  using  a  porcelain  crown  or  porcelain  facing.     The  reason 


262  REMOVABLE  BRIDGE-WORK 

for  this  is  that  in  the  case  of  an  inlay  abutment  the  tube,  starting 
as  it  does  considerably  above  the  gingival  line,  it  is  not  necessary 
that  it  should  go  to  a  greater  depth  than  about  one-third  or  one- 
half  the  length  of  the  root  below  the  gingivae,  so  that  it  occupies 
only  the  broadest  and  heaviest  part  of  the  root. . 

In  the  central  incisor,  a  No.  4  tube  may  be  used  and  at  times 
even  a  No.  5.  A  No.  5  tube  is  generally  indicated  for  the  cuspids. 
The  canal  is  enlarged  somewhat  lingually  so  as  to  give  the  tube 
a  slope  in  that  direction  which  will  allow  plenty  of  metal  between 
it  and  the  labial  side  of  the  cavity  and  permit  of  this  being  cut 
away  for  the  reception  of  the  second  inlay. 

The  cavity  is  moistened  and  the  tube  with  the  mandrel  in  it  is 
placed  in  the  root  and  pressed  well  lingually  so  that  it  clears  the 
incisal  edge  of  the  tooth  by  a  good  margin  (Fig.  471)7 
The  cavity  is  then  filled  with  wax,  the  wax  being 
flowed  in  hot  so  that  it  will  pass  around  the  tube  and 
become  well  attached  to  it.  The  cavity  should  be  well 
filled  and  the  wax  carved  so  as  to  reproduce  the 
natural  contour  of  the  lingual  surface  of  the  tooth. 

It  will  be  found  on  removing  the  inlay  and  replacing 

it  again  in  the  cavity  that  the  shrinkage  of  the  wax 

on  cooling  has  opened  the  margins,  especially  at  the 

gingival  end.     The  wax  should  be  trimmed  lightly  so 

as  to  enlarge  this  space  a  little  and  the  inlay  is  then 

replaced  and  fresh  wax  flowed  in  the  crevice. 

Fig.  471  The  wax  should  then  be  smoothed  flush  with  the 

sides  of  the  tooth  and  a  little  more  wax  flowed  over 

the  margins  so  as  to  leave  something  of  a  feather  edge,  after  which 

it  is  again  removed  from  the  tooth  and  prepared  for  casting. 

The  mandrel  is  grasped  in  the  pin-vise  and  some  of  the  wax 
carefully  trimmed  away  from  around  the  mouth  of  the  tube 
where  the  cavity  will  be  made  for  the  second  inlay,  as  shown  in 
the  illustration  (Fig.  472),  after  which  the  mandrel  is  removed. 
This  should  be  done  very  carefully  so  as  not  to  mar  or  distort 
the  inlay.  The  mandrel  being  held  in  the  pin-vise,  a  sharp  instru- 
ment is  placed  against  the  end  of  the  tube  and  it  is  in  this  manner 
forced  off  from  the  mandrel.  In  removing  it,  it  is  well  to  hold  it 
over  a  napkin  or  some  soft  material,  so  that  should  it  drop  from 
the  mandrel  there  would  be  no  danger  of  marring  the  edges. 

The  sprue  wire  is  then  attached  to  the  lingual  side  at  tbe  point 
shown  in  the  illustration  (Fig.  473).     The  lower  end  of  the  tube  is 


IXLAY  ABUTMENTS  2()3 

held  in  the  pin-vise  and  the  tube  carefully  filled  with  asbestos  paper 
or  material  of  a  similar  nature,  so  that  in  casting  there  will  be  no 


Fig.  472  pi^;.  473 


possibility  of  any  of  the  metal  forcing  its  way  into  the  tube.  The 
inlay  is  then  flashed  and  cast.  For  these  inlays,  the  writer  prefers 
pure  gold  as  with  it,  much  more  perfect  margins  can  be  secured 
than  is  possible  with  any  alloy.  If  they  are  carefully  made,  after 
setting,  the  pure  gold  inlay  can  be  burnished  and  finished  so  as  to 
entirely  obliterate  any  line  of  cement. 

The  inlay  having  been  cast,  is  removed  from  the  investment  and 
carefully  cleaned,  hydrofluoric  acid  being  used  to  remove  any 
traces  of  silica  which  may  be  clinging  to  its  surface. 

The  asbestos  paper  is  removed  from  the  tube  and  the  tube 
carefully  cleansed  and  dried.  It  is  then  ready  to  form  the  cavity 
for  the  second  inlay. 

It  should  be  placed  in  the  mouth  and  articulated,  enough  of  the 
gold  being  cut  away  so  as  to  clear  the  occlusion,  after  which  it  is 
removed  and  the  cavity  is  made  for  the  second  inlay.  This  is 
done  before  taking  the  final  impression  and  articulation,  as  by 
making  the  cavity  at  this  time  it  forms  a  seat  which  will  be  a 
guide  when  replacing  it  in  the  plaster  impression  after  it  has  been 
removed  from  the  mouth. 

The  cavity  for  the  second  inlay  is  shaped  in  the  same  manner 
as  that  for  the  first  inlay,  allowing  a  sufficient  margin  of  gold  to 
remain  at  all  points  to  give  the  required  strength  to  the 
attachment  (Fig.  474).  The  cavity  is  smoothed  so  that 
there  will  be  no  sharp  edges  which  will  scrape  the  ])laster, 
after  whicli  the  inlay  is  replaced  in  the  mouth,  and  the 
impression  and  articulation  taken.  After  the  impression 
has  been  removed  from  the  mtnith,  the  inlay  is  carefully 
replaced  in  it,  and  great  care  should  be  exercised  to  be  i'"^-  '^''4 
certain  that  it  goes  exactly  into  its  proper  position. 

It  is  then  firmly  fastened  in  i)lace  at  two  or  three  points  at  the 
margins  with  a  little  sticky  wax,  after  which  u  thin  film  of  j)arafl^n 
and  wax  is  plarcd  arouiul  tlic  tnbc.    The  whole  inlay  is  then  given 


264  REMOVABLE  BRIDGE-WORK 

a  coating  of  cocoa-butter  and  the  impression  having  been  varnished, 
the  model  is  made  and  articulated  in  the  same  manner  as  for  an 
ordinary  bridge. 

After  the  model  has  been  separated  from  the  impression,  the 
inlay  is  removed  by  heating  it  slightly  and  in  this  case  it  is  better 
that  the  model  should  be  thoroughly  dried,  and  hardened,  at  least 
around  the  tooth  which  received  the  inlay.  This  can  be  done, 
after  drying,  by  soaking  it  with  thin  sandarac  varnish. 

The  finishing  touches  are  now  given  to  the  inlay,  by  replacing 
it  on  the  articulated  model  and  grinding  a  little  wherever  neces- 
sary. The  cavity  in  the  inlay  can  readily  be  changed  to  suit  the 
existing  conditions.  It  should  then  be  made  perfectly  smooth 
and  the  constriction  at  the  neck  of  the  tube  removed  with  a  flame- 
shaped  bur,  so  that  the  mandrel  over  which  the  tube  was  made 
will  enter  freely.  The  finishing  bur.  Fig.  418,  is  best  suited  for  this 
purpose.  The  entrance  to  the  tube  is  rounded  somewhat  with  the 
same  bur. 

The  cavity  can  be  smoothed  ready  for  the  pumice  by  using  very  fine 
carborundum  stones,  or  dull  finishing  burs,  those  of  the  pear-shape, 
or  rose-bur,  being  indicated,  and  if  they  are  used  wet,  they  will  finish 
it  much  more  smoothly  than  if  they  are  dry.  A  sharp  bur  will 
not  finish  the  cavity  nearly  as  well  as  will  a  dull  one,  and  the  writer 
when  in  need  of  a  bur  for  finishing  purposes  and  having  only  new 
ones  at  hand,  make  it  a  custom  to  smooth  them  a  little  by  running 
them  over  an  Arkansas  stone  before  using  them  on  the  inlay. 
After  having  been  made  smooth  with  the  burs  and  being  made 
perfectly  symmetrical,  the  cavity  is  finished  with  pumice  and 
rouge.  This  can  best  be  done  by  using  a  wooden  point  in  an  engine 
port  polisher  and  after  roughening  the  point  somewhat,  wrapping 
a  little  cotton  around  it  so  that  it  will  carry  the  smoothing  and 
polishing  powder. 

The  Fitting  of  the  Split  Pin.^ — The  next  step  is  to  fit  the  split 
pin.  The  pin  is  made  in  the  manner  which  will  be  described  later, 
with  the  exception  that  it  is  made  about  twice  the  length  of  the 
tube,  and  the  point  of  contact  is  also  long,  as  shown  in  the  illustra- 
tion (Fig.  475),  so  that  the  point  of  union  where  the  pin  has  been 
soldered  will  come,  when  it  is  finished,  just  below  the  floor  of  the 
cavity.  It  is  carefully  fitted  to  the  tube  and  should  fit  it  just 
about  as  easily  as  the  pin  should  fit  the  tube  for  an  anterior  crown. 

It  is  then  annealed  and  placed  in  the  tube  and  a  mark  made  just 
at  the  entrance  from  the  floor  line  at  point  a,  Fig.  476.    It  is  now 


INLAY  ABUTMENTS  265 

removed  and  placed,  the  finished  closed  end  first,  in  the  pin-vise, 
carrying  it  in  about  one-thirty-second  of  an  inch  farther  than  the 


Fig.  475  Fig.  476 

mark  showing  the  floor  line.  The  vise  should  be  tightened  firmly 
and  the  pin  bent  over  by  pressing  it  against  the  edge  of  the  bench, 
or  by  catching  the  end  in  a  pair  of  pliers. 

After  bending  it  part  way,  it  is  best  to  re-anneal  it  before  the 
bending  is  finished.  The  pin  is  then  bent  nearly  at  right  angles 
or  even  farther  so  that  it  will  follow  the  general  direction  of  the 
cavity  (Fig.  477). 

The  pin  should  be  bent  in  the  direction  of  the  split,  as  if  it  is 
bent  across  the  split,  should  it  be  held  in  the  pin-vise  very  close  to 


Fig.  477 

the  soldered  point  of  union,  there  is  a  possibility  of  breaking  this 
union  and  one  of  the  halves  sliding  upon  the  other  and  thus  destroy- 
ing the  fit  of  the  pin. 

The  pin,  having  been  bent  to  its  proper  shape,  is  filed  open  at 
the  end,  care  being  taken  to  file  it  in  the  direction  of  the  split  and 
the  end  is  nicely  rounded.  Every  thing  is  now  ready  for  the  making 
of  the  «ec-ond  inlay. 

The  Second  Inlay. — The  second  iiila\'  siioiild  be  made  of  a  liardcr 
metal  than  the  first,  such  as  coin  gold,  or  some  alloy  equally  hard 
and  which  fuses  at  al)out  the  same  temperature  as  does  the  coin 
gold. 

The  second  inlay  may  be  made  by  inserting  the  pin  in  the  tube, 
building  it  up  with  wax  and  casting,  but  this  will  not  make  as 
perfect  an  inlay  as  can  be  made  in  the  manner  described  below, 
but  it  can  be  used  if  desircfl. 


266  REMOVABLE  BRIDGE-WORK 

The  method  which  the  writer  prefers  in  making  a  second  inlay 
is  to  first  burnish  a  pure  gold  matrix  into  the  cavity  and  after- 
ward fill  the  matrix  with  coin.  The  pure  gold  should  be  of  about 
No.  36  gauge,  great  care  being  used  in  the  burnishing  to  have  the 
margins  as  nearly  perfect  as  possible.  It  should  be  annealed  very 
frequently  during  the  operations  and  worked  in  very  slowly,  as  in  a 
cavity  of  this  kind,  if  the  metal  becomes  the  least  bit  hard  from 
burnishing,  it  is  easily  cracked. 

After  the  matrix  has  been  burnished  in,  a  hole  is  made  over  the 
entrance  to  the  tube,  so  that  the  pin  will  pass  through  the  matrix 
and  enter  the  tube  freely.  This  having  been  done  and  the  pin  and 
matrix  having  been  removed,  the  cavity  and  entrance  to  the  tube 
are  given  a  light  coating  of  cocoa-butter.  The  matrix  is  then 
annealed  and  it  and  the  pin  placed  in  position,  the  edges  of  the 
pure  gold  extending  beyond  the  sides  of  the  cavity,  and  the  cavity 
is  filled  with  a  hard,  sticky  wax.  The  wax  should  be  run  in  hot  so 
that  it  will  pass  all  around  and  under  the  pin,  and  after  it  has  been 
chilled  it  should  be  pressed  tightly  down  around  the  pin  and  over 
the  margins,  forcing  the  pure  gold  matrix  in  close  contact  with 
the  edges  of  the  cavity.  It  is  then  removed  and  is  ready  for 
investment. 

It  is  invested  as  shown  in  Fig.  478,  and  only  a  sufficient  amount 
of  the  investment  used  to  hold  the  parts  in  position.     The  over- 


%;A 


Fig.  478 

lapping  edges  of  the  matrix  should  be  covered,  but  the  investment 
should  not  be  carried  over  the  cavity  margins.  It  is  then  heated-up 
to  a  red  heat. 

A  button  of  coin  gold  of  sufficient  size  to  fill  the  matrix  should 
then  be  made  and  laid  over  the  pin,  the  whole  heated  up  well  and 
the  button  melted  into  the  matrix  so  that  it  will  fill  it  a  little  more 
than  flush,  the  same  as  in  filling  a  cusp,  after  which  the  inlay  is 
removed  from  the  investment  and  well  cleansed  in  acid. 

It  is  then  dried,  replaced  in  the  inner  inlay  and  finished.  It  should 
be  ground  perfectly  flush  with  the  margins  and  from  the  second 


INLAY  ABUTMENTS 


26: 


Fig.  479 


inlay  to  the  outer  edges  until  it  is  finished  and  properly  contoured. 
It    should    be  remembered    that   the  cutting  should  be   from   the 
center  outward   (Fig.  479),  as  if  it  were  ground  in  the  opposite 
direction,  the  gold  in  the  outer  inlay  would  be  burnished 
over  the  second  inla>'  so  that  it  would  be  impossible  to 
separate  them.     It  is  now  ready  for  attachment  to  the 
bridge. 

This  work  is  done  on  the  model  and  after  all  of  the 
parts  of  the  bridge  are  assembled  they  are  waxed  to- 
gether, care  being  taken  to  wax  it  thoroughly  to  the 
extending  pin  of  the  inlay.  The  piece  is  chilled  and  the 
inner  inlay  removed  from  the  otiter  by  grasping  the  tube  and 
pressing  against  the  pin  with  a  fine-pointed  instrument  or  the  edge 
of  a  knife  blade  exercising  great  care  not  to  use  force  at  any  other 
point,  otherwise  the  relation  of  the  bridge  and  inlay  might  be 
disturbed. 

Before  investing  it  for  the  final  soldering,  the  inlay  should  be 
coated  well  with  antiflux  (common  whiting  will  answer  for  this 
purpose),  which  will  prevent  the  solder  from  flowing  over  the 
margins  and  destroying  the  fit  of  the  inlay.  In  finishing  the  piece, 
great  care  should  be  exercised  not  to  polish  the  pin  or  the  inside 
of  the  inlay.  An  old  tube  placed  over  the  pin  during  the  finishing 
of  the  bridge  will  prevent  any  injury  to  it. 

Inlays  for  Molars. — The  cavities  for  the  inlays  for  molars  should 
be  large  and  take  in  a  good  part  of  the  occlusal  surface  (Fig.  480) 
extending  on  the  side  to  which  the  bridge  is  to  be  attached  down 
to  near  the  gingivae,  as  shown  in  the  illustration  (Figs.  481  and 
482). 


Fio.  480 


Fio.  481 


Fig.  482 


''i'he  cavity  is  made  non-retentive,  and  if  there  should  be  any 
undercuts,  they  may  be  fill(>d  in  temporarily  with  gutta-percha 
or  cement. 

The  tubes  for  the  molars  should  extend  to  the  floor  of  the  pulp 
chanibcr  and  occasionally  it  may  be  necessary  to  deepen  it  on  the 


268  REMOVABLE  BRIDGE-WORK 

mesial  side,  letting  it  drop  into  the  root  a  short  distance,  as  in  the 
case  of  a  telescope  crown  with  a  tube  and  split  pin. 

It  is  desirable  in  these  cases  that  pure  gold  should  be  used  next 
to  the  tooth  structure  so  that  a  more  perfect  margin  may  be 
obtained.  As  a  general  rule  the  pure  gold  should  be  about  one- 
thirty-second  of  an  inch  in  thickness,  and  this  will  serve  as  a  matrix 
for  the  making  of  the  main  body  of  the  inlay.  A  very  thin  piece 
of  wax,  the  pink  paraffin  and  wax  will  answer  nicely,  and  can  be 
readily  worked  into  the  cavity,  covering  the  margins  perfectly. 
The  sprue  wire  is  attached  to  the  distal  end  of  the  wax  matrix 
(Fig.  482),  which  is  then  removed  (Fig.  483),  flasked  and  cast  in 
pure  gold  in  the  same  manner  as  an  ordinary  inlay.  It  has  been 
the  general  custom  of  the  writer,  however,  to  do  this  by  the  indirect 
method,  obtaining  an  impression  of  the  cavity  and  then  making 
an  amalgam  die  over  which  to  make  the  inlay. 

The  die  having  been  prepared,  the  wax  matrix  is  made  of  the 
desired  thickness  and  fitted  in  the  tooth  before  casting,  being  pressed 


Fig.  483  Fig.  484  Fig.  485 

firmly  against  the  margins.  The  matrix  need  not  extend  entirely 
to  the  bottom  of  the  cavity  as  it  is  only  necessary  that  perfect 
margins  be  obtained,  and  that  it  be  of  sufficient  depth  to  give  body 
to  the  inlay,  as  in  Fig.  484. 

The  matrix  having  been  cast  in  pure  gold,  it  is  fitted  in  the  tooth 
and  the  edges  tapped  in  place  with  a  stick  of  cottonwood  so  as  to 
make  sure  that  the  edges  are  in  perfect  contact  with  the  margins 
of  the  cavity.  A  hole  is  then  made  through  the  floor  of  the  matrix 
over  the  point  at  which  the  tube  will  rest  (Fig.  485).  This  hole 
should  be  considerably  larger  than  the  diameter  of  the  tube,  which 
is  to  be  used.  Pink  paraffin  and  wax  is  then  pressed  through  the 
opening  to  the  bottom  of  the  cavity  in  the  tooth  and  pressed  in 
over  the  floor  of  the  matrix  so  that  it  will  be  firmly  attached  (Fig. 
486).    The  impression  and  articulation  is  then  taken. 

The  impression  having  been  removed  from  the  mouth,  the  gold 
matrix  is  removed  from  the  tooth,  great  care  being  taken  not  to 
disturb  the  wax.    This  is  replaced  in  the  impression  and  caught  at 


I  XL  A  Y  AB U TMENTS 


269 


Fig.  486 


two  or  three  points  with  sticky  wax  so  that  it  cannot  shift  its  posi- 
tion. The  impression  is  then  varnished  and  the  underside  of  the 
inlay  given  a  Hght  coating  of  cocoa-butter  and  the 
model  is  prepared.  After  it  has  been  separated,  the 
inlay  and  wax  are  removed  and  the  model  dried  and 
hardened.  The  inlay  is  replaced  on  the  model,  the 
wax  which  was  beneath  it  ha\ing  gWen  a  perfect  re- 
production of  the  shape  of  the  cavity. 

The  inside  of  the  matrix  should  now  be  coated  very 
lightly  with  cocoa-butter  so  that  the  wax  will  draw 
easily.  The  tube,  with  the  mandrel  inserted,  is  then 
placed  in  the  cavity  extending  through  the  opening  in  the  matrix 
to  the  floor  of  the  pulp  chamber  or  the  bottom  of  the  cavity  which 
has  been  made  to  receive  it,  and  the  inside  of  the  matrix  filled 
with  inlay  wax,  running  it  in  hot  so  that  it  will  attach  itself  to  the 
tube  (Fig.  487). 

The  tube  resting  on  the  floor  of  the  pulp  chamber  can  be  made 
parallel  with  the  anterior  abutment  hx  leaving  the  mandrel  in 
any  direction  desired,  the  bottom  of  the  tube  remaining  immovable 
at  the  bottom  of  the  pulp  chamber  or  cavity  (Fig.  487). 


Fic.  4S7 


Fig.  488 


The  wax  should  then  be  cut  a\va>'  from  around  the  top  of  the 
tube,  roughl.\'  shaping  the  caxity  for  the  final  inlay  and  the  sprue 
wire  attached  on  tlic  mesial  side,  as  in  Fig.  488. 

It  is  tfieii  reinoNcd  from  the  pure  gold  matrix  and  the  mandrel 
remo\fd  from  the  tube  which  is  packed  with  asbestos  \ni])vT  in  the 


270  REMOVABLE  BRIDGE-WORK 

manner  previously  described.  It  is  next  flasked  and  cast  with  coin 
gold,  after  which  it  is  well  cleansed  in  hydrofluoric  acid.  After 
cleaning  and  drying,  it  is  placed  in  the  pure  gold  matrix  in  order  to 
ascertain  that  it  fits  perfectly.  The  underside  of  the  matrix  is 
covered  with  whiting  so  that  no  solder  will  flow  over  and  destroy 
the  fit  in  the  tooth  and  the  two  are  united  with  21 -carat  solder, 
the  solder  being  placed  at  some  point  between  the  pure  gold  matrix 
and  the  coin,  as  at  point  a  in  Fig.  489,  and  drawn  through  entirely 
from  that  point  until  the  pure  gold  and  coin  are  perfectly  united. 
The  cavity  is  now  ready  to  be  prepared  for  the  final  inlay. 


Fig.  489  Fig.  490 

The  tube  is  cut  off  to  the  floor  of  the  cavity  and  the  coin  gold 
cut  away,  making  the  cavity  a  little  larger  around  the  tube,  giving 
it  something  the  shape  of  a  key-hole,  looking  from  the  occlusal 
surface,  so  that  it  will  not  be  necessary  to  depend  entirely  upon  the 
split  pin  for  retention  (Fig.  490). 

The  cavity  is  finished  so  that  it  is  perfectly  symmetrical  in  shape 
and  then  polished,  the  entrance  to  the  tube  having  been  opened 
so  that  the  mandrel  over  which  it  was  made  will  enter  freely. 
The  pure  gold  matrix  is  burnished  in  place,  the  pin  fitted  to  it  and 
the  inlay  completed  in  the  manner  already  described  in  the  making 
of  the  anterior  abutments. 

Before  cementing  the  inlay  in  place,  any  gutta-percha  or  cement 
which  has  been  placed  in  the  tooth  to  obliterate  undercuts,  should 
be  removed  in  order  that  the  inlay  may  become  firmly  attached 
with  cement. 

It  is  an  advantage  to  have  the  bridge  worn  for  from  twenty-four 
to  forty-eight  hours  without  cementing  in  order  to  allow  for  the 
settling  of  the  piece,  and  for  the  abutments  to  accommodate  them- 
selves to  it.  Where  there  is  an  inlay  abutment  such  as  the  one 
just  described,  the  inlay  is  always  set  separately,  as  there  is  only 
one  way  in  which  an  inlay  can  go  into  place  and  it  must  go  to  its 
proper  place  or  it  will  stand  away  from  the  margins  of  the  cavity 
at  one  point  or  another  with  the  result  that  the  cement  will  wash 
out  and  decay  take  place. 


INLAY  ABUTMENTS  271 

After  it  lias  been  carefully  articulated,  finished  and  cemented, 
the  edges  of  the  pure  gold  matrix  are  burnished  over  the  edges 
of  the  cavity  and  it  is  polished  finally.  In  this  way  more  perfect 
margins  ma,\-  be  secured. 

Inlays  by  the  Matrix  Method. — In  the  absence  of  casting  machines, 
inlays  may  be  made  by  the  matrix  method  so  that  they  will  be 
as  perfect  as  those  made  by  casting.  The  cavities  are  prepared 
in  the  manner  already  described.  A  matrix  of  pure  gold,  as  heavy 
as  can  be  worked  into  the  cavity,  is  then  burnished  into  place, 
or  a  very  thin  platinum  matrix  may  be  used,  burnishing  it  in  the 
same  manner  as  for  a  porcelain  inlay.  The  matrix  must  be  carried 
over  the  cavity  margins  and  made  as  perfect  as  possible  (Fig.  491). 

The  matrix  is  then  annealed  and  put  back  in  the  tooth,  the 
tube  placed  in  position  (Fig.  491)  and  waxed  well  with  hard  sticky 
wax,  filling  the  matrix  to  the  cavity  margins.  When  the  wax  has 
cooled,  it  is  packed  tightly  in  place  around  the  margins  of  the 
cavity  so  as  to  press  the  matrix  in  perfect  contact.  The  matrix 
is  then  removed  and  the  tube  filled  with  asbestos  paper  or  fiber, 
and  the  whole  invested  (Fig  492). 


Fig.  491  Fig.  492 

If  a  pure  gold  matrix  has  been  used,  the  matrix  should  be  filled 
with  coin  gold,  but  if  the  matrix  has  been  of  platinum,  then  it  can 
be  filled  with  pure  gold.  After  cleansing  it  is  dried  out  and  the 
cavity  prepared  for  the  second  inlay,  the  technic  in  this  case  being 
exactly  the  same  as  for  the  cast  inlays,  which  has  already  been 
described. 

In  very  small  pieces,  or  in  the  anterior  part  of  the  mouth,  where 
the  teeth  are  small,  the  second  inlay  may  be  done  away  with  by 
fitting  and  bending  the  pin  so  that  it  will  rest  in  the  bottom  of  a 
groove  which  has  been  made  to  receive  it  (Fig.  493).  The  groove 
should  be  made  the  size  of  the  split  pin  which  is  to  be  used  and 
after  it  is  completed,  the  extending  end  of  the  pin  should  be  sol- 
dered into  the  bridge.    This  will  answer  the  i)urposc  aiifl  do  as  well 


272  REMOVABLE  BRIDGE-WORK 

in  carrying  a  small  bridge  as  if  there  were  a  second  inlay,  but  it 
does  not  make  quite  as  clean  a  piece,  as  there  will  be  a  groove  on 


Fig.  493  Fig.  494 

either  side  of  the  pin  as  it  rests  in  the  inlay.  Neither  is  it  quite  as 
strong,  and  where  strength  and  rigidity  are  desired  the  double  inlay 
should  be  used. 

Inlay  abutments  may  sometimes  be  used  in  the  lower  bicuspids, 
especially  if  they  are  made  so  as  to  restore  a  part  or  the  whole  of 
the  occlusal  surface  of  the  tooth,  in  which  case  the  tooth  is  beveled 
from  the  inside  outward  and  downward  toward  the  gum,  as  is 
Fig.  494,  and,  as  will  be  seen,  there  is  practically  no  possibility  of 
the  tooth  being  fractured  by  the  pressure.  In  the  upper  bicuspids, 
however,  the  inlay  is  very  rarely  indicated,  as  the  crowns  of  these 
teeth  are  never  very  strong  and  very  little  force  would  be  required 
to  bring  about  their  fracture. 

SUPPORTING  ABUTMENTS. 

The  anchorages  so  far  described  have  been  retaining  abutments 
and  the  supporting  abutments  will  now  be  considered.  As  pre- 
viously stated,  the  supporting  abutment  gives  support  against 
vertical  and  lateral  stress  and  has  nothing  to  do  with  the  retention 
of  the  bridge. 

Supporting  abutments  may  be  in  the  form  of  gold  fillings  or 
of  inlays,  the  gold  fillings  being  countersunk  to  receive  the  spur. 
A  hooked  spur  of  platinized  gold  or  iridio-platinum  resting  in  a 
countersunk  gold  filling  or  an'  inlay  forms  an  excellent  support 
for  one  end  of  a  bridge.  This  is  especially  the  case  in  the  lower' 
jaw,  where  it  will  safely  support  one  end  of  a  bridge  consisting 
of  two  or  three  or  even  more  teeth  and  having  but  a  single  retain- 
ing abutment. 

In  the  upper  jaw,  with  a  crown  carrying  a  single  dummy,  the 
other  end  may  be  supported  by  a  spur  in  countersunk  filling  or 
an  inlay.     They  are  often  useful,  too-,  in  giving  extra  stability  to 


SUPPORTING  ABUTMENTS  273 

a  larger  bridge  which  has  two  or  more  retaining  abutments,  but 
which  may  require  some  additional  support. 

Gold  Fillings. — Where  a  spur  is  to  rest  in  a  filUng  in  any  of  the 
anterior  teeth,  either  upper  or  lower,  the  ca\ity  is  made  in  the 
palatal  or  lingual  side  of  the  tooth  and  also  extending  for  a  distance 
over  the  side  next  to  the  bridge,  as  in  Fig.  495.  Where  the  bite 
does  not  interfere,  the  cavity  is  made  just  at  the  basilar  ridge 
where  the  enamel  is  very  thick,  and  should  be  of  good  size, 
approximately  about  one-eighth  of  an  inch  in  diameter. 

The  cavity  should  be  started  with  a  small  carborundum  wheel, 
plenty  of  water  being  used  to  cut  through  the  enamel  and  give  the 
general  outline  to  it,  before  putting  on  the  rubber  dam.  The 
rubber  dam  having  been  adjusted,  the  cavity  is  deepened  with 
burs  as  much  as  possible  without  endangering  the  pulp.  The 
cavity  is  well  undercut  and  a  filling  of  hard  gold,  thoroughly  con- 
densed, is  inserted.     It  is  made  large  enough  so  that  the  contour 


Fiu.  495  Fig.  4'JG  Fig.  497 

of  the  tooth  is  somewhat  exaggerated,  as  in  Fig.  4()(),  but  not 
enough  to  interfere  with  the  articulation. 

The  filling  is  then  polished  and  a  hole  drilled  in  the  center  of 
it  on  the  palatal  side  to  within  a  short  distance  of  the  bottom  of  the 
cavity,  the  base  of  the  hole  being  shaped  with  a  bud-shai)ed  bur 
about  the  size  of  the  No.  14  to  IG  gauge  wire  of  which  the  spur  will 
l)e  made.  A  groove  of  the  same  size  is  then  cut  from  this  ()])ening 
to  the  distal  side  of  the  filling,  care  being  taken  to  allow  a  strong 
borjy  of  gold  remain  underneath  and  around  it  so  as  not  to  weaken 
the  filling  (Fig.  497,  a  b). 

IJefore  taking  the  impression,  a  small  amount  of  ])ink  wax  is 
pointed  and  pressed  into  the  bottom  of  the  cavity  and  into  the 
groove,  and  the  impression  taken  in  plaster  in  the  ordinary  maimer. 
When  the  impression  is  removed  from  the  mouth,  the  pink  wax 
will  come  away  with  it,  giving  a  perfect  im[)ressi()n  of  the  cavity 
and  groove  in  the  filling.     If  the  impnjssion  is  taken  without  the 


274  REMOVABLE  BRIDGE-WORK 

wax,  the  fine  point  of  plaster  extending  to  the  bottom  of  the  cavity 
will  be- broken  away  and  will  not  give  a  perfect  impression  in  the 
model.  The  model  is  then  made  and  after  it  has  been  trimmed  and 
hardened,  the  fitting  of  the  spur  and  the  balance  of  the  work  is 
done  on  it. 

The  Inlay  as  a  Support. — In  using  a  gold  inlay  as  a  support  for 
the  spur,  the  operation  is  simplified,  and  the  spur  can  be  made  of 
any  shape  desired  with  a  certainty  of  its  fitting  the  cavity  properly, 
A  slight  notch  or  groove  is  made  in  the  tooth,  before  taking  the 
impression,  where  it  is  desired  that  the  spur  should  rest,  in  order 
that  the  position  on  the  model  which  the  spur  is  to  occupy  may  be 
located.  The  spur  may  be  in  the  form  of  a  hook,  especially  in  the 
anterior  part  of  the  mouth  (Fig.  498),  or  in  the  form  of  a  dovetail 


Fig.  498  Fig.  499 

(Fig.  499).  The  latter  is  especially  applicable  in  the  case  of  the 
molars  where  greater  strength  is  required. 

The  object  in  making  the  spur  in  the  shape  of  a  hook  or  dove- 
tail rather  than  having  it  straight  and  flat,  is  that  it  may  bind  the 
teeth  together  so  that  there  is  no  possibility  of  their  spreading, 
which  might  happen  should  there  be  a  smooth  piece  of  wire  resting 
in  a  groove. 

The  plaster  tooth  is  cut  away  sufficiently,  at  the  point  indicated 
by  the  notch  or  groove,  to  allow  for  the  resting  of  the  spur,  and  the 
bridge  is  constructed  with  the  spur  made  so  as  to  rest  in  the  cavity. 
When  the  bridge  is  completed,  the  natural  tooth  is  cut  away  roughly, 
where  the  spur  is  to  rest,  so  as  to  allow  the  bridge  to  drop  into 
its  proper  position.  It  is  well  to  allow  the  patient  to  wear  the 
bridge  for  a  day  or  two  before  cementing. 

When  the  bridge,  if  it  be  removable,  has  been  cemented,  and 
the  cement  thoroughly  hardened,  it  is  removed  from  the  mouth 
and  the  making  of  the  inlay  undertaken.  The  cavity  for  the  spur 
is  enlarged  sufficiently  to  allow  of  a  good  bulk  of  gold  on  all  sides, 
extending  well  down  on  the  approximal  side  of  the  tooth.  On  this 
side  the  cavity  can  be  made  very  shallow,  as  there  is  no  strain 
here  and  the  gold  over  this  surface  is  simply  to  protect  the  tooth 
from  decay,  which  is  very  necessary  in  the  case  of  fixed  bridges, 
but  not  so  important  where  the  bridge  is  removable. 


SlirrORTING  ABVTMKNTS  275 

The  sides  of  the  cavitN-  should  he  made  as  nearly  parallel  as 
l)ossihle.  hut  it  must  he  made  non-retentive.  The  wax  is  then  placed 
in  the  cavity  and  the  hridgc*  slightly  warmed  and  j)laced  in  position, 
the  spur  pressing  its  way  into  the  wax.  The  wax  is  then  trinnned 
to  the  margins  of  the  cavity.  The  bridge  is  removed  and  rci)lace(l 
several  times  in  order  to  be  positive  that  the  spur  has  made  a  good 
seat. 

The  s])rue  wire  is  then  fastened  to  the  wax,  which  is  remox'ed 
from  the  tooth,  invested  and  cast,  either  with  pure  gold  or  an 
alloy.  After  it  has  been  cast  and  cleansed,  it  is  first  tried  in  the 
cavit\'  and  the  bridge  is  adjusted  to  it.  It  is  then  removed,  the 
sides  roughened,  the  cavity  undercut  slightly,  and  the  inlay 
cemented.  After  the  cement  has  thoroughly  set,  the  inlay  is  care- 
fully polished  and  the  bridge  placed  in  the  mouth.  In  the  case  of 
a  fixed  bridge,  the  inlay  is  i)repared  before  the  final  cementing. 

By  making  the  inlay  in  the  manner  descri})ed,  it  is  certain  that 
the  spur  is  perfectly  seated,  which  is  not  always  the  case  where  the 
gold  filling  has  been  used  as  a  rest. 


CHAPTER  XIII. 
TUBES  AND   SPLIT   PINS. 

Among  the  most  important  accessories  in  removable  bridge-work 
are  the  tubes  and  split  pins.  In  order  that  they  be  effective,  it  is 
necessary  that  they  should  be  made  with  the  greatest  accuracy. 
The  tubes  should  be  perfectly  round  and  smooth  on  the  inside  and 
the  split  pins,  which  are  to  be  used  in  them,  should  be  made  so  as 
to  fit  perfectly,  otherwise  they  will  be  of  but  little  value. 

The  metal  of  which  the  tubes  are  made  should  be  hard, 
tough,  rigid  and  non-oxidizable.  The  best  alloy  for  the  purpose 
is  iridio-platinum,  the  alloy  containing  approximately  10  per 
cent,  of  iridium.  If  the  dentist  is  specializing  in  bridge-work, 
or  is  doing  a  large  amount  of  it,  it  would  perhaps  be  better  and 
cheaper  to  have  the  tubing  made  by  a  platinum  manufacturer 
who  makes  a  specialty  of  work  of  this  character.  Should  this 
not  be  the  case,  the  tubes  may  easily  be  made  by  the  operator. 
When  the  writer  first  began  the  making  of  removable  bridge-work, 
he  made  his  tubes  by  drilling  a  solid  iridium-platinum  wire  with  a 
twist  drill  of  suitable  size  on  a  jewler's  lathe.  It  developed,  however, 
that  a  drilled  tube  was  not  a  good  tube.  It  makes  little  difference 
how  sharp  the  drill  may  be,  or  how  smoothly  it  cuts,  the  tube  will 
always  be  rough  on  the  inside,  the  drill  leaving  a  minute  thread 
which,  no  matter  how  fine  it  may  be,  will  wear  down  quickly,  and 
entirely  destroy  the  fit  of  the  pin  in  the  tube.  Tubes  may  be  made 
with  a  draw  plate,  but  a  drawn  tube  is  never  perfectly  straight, 
and  before  using  them,  it  is  necessary  to  drive  a  mandrel  through 
in  order  to  straighten  them. 

Making  Tubes  by  the  Mandrel  Process. — A  simple  and  easy  method 
of  making  a  good  tube  and  one  which  the  writer  has  largely 
employed  for  a  number  of  years,  consists  of  working  them  over 
steel  rods  or  mandrels  made  for  the  purpose  and  is  as  follows: 

The  Mandrels. — The  set  consists  of  six  mandrels  made  from 
regular  sizes  of  Stubb's  steel  wire,  which  can  be  procured  at  dealers 
in  machinists'  and  jewelers'  supplies.  The  gauge  numbers  run 
from  48  to  53  inclusive,  the  sizes  of  the  wire  being,  respectively, 
.075,  .072,  .069,  .066,  .063  and  .058  of  an  inch  in  diameter. 


THE  MANDRELS  2/7 

These  rods  are  cut  in  lengths  of  about  one  and  one-hah'  inches, 
and  the  ends  carefully  rounded.     For  convenience,  they  may  be 
numbered  from  one  to  six,  by  marking  them  with  rings  around  one 
end,  according  to  the  size  of   the  mandrel, 
beg'inning  with  the  smallest,  Nos.  1,  2,  3,  4, 
etc.  (Fig.  500). 

In  tempering  the  mandrels,  they  should  be 
heated  to  a  cherry  red  (it  is  best  to  heat  them 
on  a  charcoal  block),  and  then  plunged  in 
water  to  harden  them.  In  plunging  them  in 
the  water,  they  should  be  grasped  with  the 
pliers  by  one  end  so  that  they  will  hang  verti- 
cally and  enter  the  water  in  this  position.  If 
they  are  plunged  in  sideways,  so  that  one  side 
of  the  mandrel  becomes  chilled  before  the  other,  fig.  oOO 

they  are  more  apt  to  be  sprung  or  distorted. 

They  are  then  dried  off  and  polished  with  cuttlefish  or  other 
very  fine  grit  paper.  The  heating  and  chilling  having  made  them 
extremely  hard  and  brittle,  it  will  be  necessary  to  soften  them 
somewhat  to  prevent  their  breaking,  which  may  be  done  preferably 
by  laying  the  mandrels  on  a  piece  of  heated  metal  until  they  assume 
a  color  indicating  the  desired  temper,  when  they  should  be  again 
plunged  into  cold  water  endwise.  The  mandrels  should  be  of  a  high 
spring  temper  and  should  be  drawn  down  until  the  color  is  between 
a  deep  straw  and  a  pigeon  blue.  This  gives  them  the  right  degree 
of  hardness,  after  which  they  may  again  be  polished,  or  they  can 
be  used  without  polishing. 

It  is  a  good  plan  when  the  mandrels  are  first  heated  up,  before 
they  become  red,  to  plunge  them  into  a  cake  of  soap  and  then 
proceed  to  heat  them  up  to  a  cherry  red.  This  will  prevent  oxidation 
of  the  metal,  and  they  will  come  out  cleaner  than  they  otherwise 
would. 

Another  method  of  j^rocedure  for  the  beginner,  or  for  those  not 
familiar  with  tempering  steel,  and  which  will  perhaps  answer  the 
purpose  for  which  the  mandrels  are  intended,  is  to  bring  them  to 
a  cherry-red  heat  and  then  plunge  them  into  a  heavy  oil.  They 
are  next  held  in  the  (fame  of  an  alcohol  lamp  or  a  Buiisen  l)uriier 
until  the  oil  is  burned  off,  and  then  j>lunged  into  water.  This 
will  soften  the  mandrels  so  that  they  will  have  a  fair  spring  temper. 
After  the  oil  is  burnt  off,  they  should  be  carefully  smootlied  and 
polished. 


278 


TUBES  AND  SPLIT  PINS 


The  Tubes. — The  material  of  which  the  tube  is  to  be  made, 
iridio-platinum  plate,  containing  about  from  7  per  cent,  to  10  per 
cent,  iridium  and  of  No.  32  gauge  or  .008  of  an  inch  in  thickness. 
If  the  plate  is  about  seven-sixteenths  of  an  inch  wide,  it  will  be 
of  sufficient  width  to  give  ample  length  for  any  tube  that  may 
be  required.  The  strip  should  be  cut  lengthwise  with  the  grain 
of  the  metal  as  it  has  passed  through  the  rolling  mill. 

In  making  the  tube,  the  plate  is  first  annealed,  the  end  squared, 
and  beveled  with  a  fine  file  to  a  knife  edge  (Fig.  501).    A  hammer- 


FiG.  501 


headed  hand-vise  is  necessary  in  making  the  tubes,  as  it  is  very 
strong,  and  the  jaws  open  and  close  on  perfectly  parallel  lines 
(Fig.  502).    The  serrations  should  be  ground  off  so  as  to  leave  the 


Fig.  502 


jaws  perfectly  smooth  on  the  inside,  and  the  outer  edge  of  one  of 
the  jaws  should  be  slightly  rounded.     The  end  of  the  iridio-plati- 


FiG.  503 


num  plate  is  grasped  in  the  jaws  of  the  hand-vise  and  bent  slightly 
upward,  the  beveled  edge  being  underneath  (Fig.  503). 


THE   TUBES 


279 


The  mandrel  is  then  hiid  across  the  iridio-])hitinum  plate,  the 
turned  up  edge  of  the  plate  ])reventing  it  from  rolling  off.  It  is  now 
grasped  by  the  hammer  headed  hand-vise,  one  jaw  engaging  the 
mandrel  and  the  other  the  upturned  edge  of  the  plate  (Fig.  504). 
The  plate  is  then  bent  around  the  mandrel,  as  shown  in  the  illus- 


FiG.  504 


tration,  until  the  beveled  edge  has  passed  the  center  of  the  mandrel, 
so  that  it  will  not  drop  out  if  it  is  raised  above  the  level  of  the 
opposite  end  (Fig.  505). 


Fig.  505 


The  plate,  with  the  mandrel  in  position,  is  next  laid  on  a  flat 
hard  surface,  such  as  the  face  of  the  anvil,  or  on  a  flat,  smooth  file. 
The  end  of  a  flat  course  file,  say  a  No.  2  cut,  is  held  in  such  a  i)osition 
as  to  catch  the  beveled  edge  of  the  platinum.  The  other  end  of  the 
plate  is  held  tightly  with  the  fingers  of  the  left  hand  and  the  file 
pres.sed  downward  and  backward  against  the  iiiiindrel,  as  is  shown 
in  Fig.  500,  the  plate  being  rolled  around  it  until  the  beveled  edge 
is  in  contact  with  the  lower  si<le  of  the  plate,  as  shown  in  the 
illustration  (Fig.  507j.      It  is   very  important  that  it  should  be 


280 


TUBES  AND  SPLIT  PINS 


rolled  only  until  the  beveled  edge  is  exactly  in  contact  with  the 
plate,  for  the  following  reasons:  It  is  desirable  to  use  as  large 
a  tube  or  pin  in  a  tooth  as  the  root  will  permit,  the  difference  in 


Fig.  506 

the  size  of  the  mandrels  is  .003  of  an  inch,  with  the  exception  of 
that  between  the  first  and  second,  in  which  the  difference  is 
.005  of  an  inch.  The  plate  used  for  making  the  tubes  is  of  No.  32 
gauge,  or  .008  of  an  inch  in  thickness.  If  in  rolling  the  tubes,  the 
lap  is  carried  beyond  the  point  of  contact,  as  shown  in  Fig.  508, 


Fig.  507 


Fig.  508 


Fig.  509 


there  will  be  an  extra  thickness  of  metal  on  that  side.  It  can  readily 
be  seen  that  this  extra  thickness  of  metal  will  give  an  outside 
diameter  of  the  tube  that  will  be  .008  of  an  inch  greater  than  it 
would  were  it  brought  exactly  in  contact  with  the  beveled  edge 
(Fig.  509).  The  result  would  be  that  the  hole  in  the  root  would 
have  to  be  made  as  large  to  accommodate  a  tube  so  made  as  though 
it  were  intended  to  use  a  much  larger  tube,  being  0.008  of  an  inch 
larger  or  nearly  the  difference  in  size  between  three  mandrels.  In 
other  words,  if  this  extra  lap  is  made  it  would  be  necessary  to 
have  an  opening  in  the  root  for  a  tube  made  over  a  No.  2  mandrel, 


THE  TUBES 


281 


as  large  as  would  be  required  for  one   which   had   been  properly 
made  and  finished  over  a  Xo.  5  mandrel. 

The  tube  having  been  rolled  in  the  proper  manner,  the  mandrel 
is  removed  and  the  seam  soldered  with  pure  gold,  no  flux  being 
used.  A  small  piece  of  pure  gold  is  laid  on  the  plate,  being  in  contact 
with  the  plate  and  lower  side  of  the  tube  (Fig.  510).      It  is  then 


Fig    .510 


soldered  by  holding  it  over  a  flame  of  a  Bunsen  burner,  first  passing 
it  through  the  flame  so  that  it  will  strike  the  plate  a  short  distance 
from  the  tube,  and  holding  it  there  until  the  gold  begins  to  melt. 
The  tube  is  then  drawn  back  into  the  flame  and  held  until  the  gold 
is  thoroughly  melted,  the  tube  is  soldered  all  the  way  across,  and 
the  gold  is  well  burned  into  the  platinum. 

If  the  tube  is  first  held  in  the  flame,  it  will  be  found  that  as  the 
pure  gold  solder  melts,  it  will  jump  up  over  the  side  and  around  the 
t(jp  of  the  tube,  but  will  n(jt  unite  it  at  the  lap.  It  is  cooled  by 
laying  it  on  a  cool  surface,  such  as  a  file  or  an  anvil.  This  will  take 
but  a  moment.  It  should  never  be  cooled  in  water,  as  should  this 
be  done,  when  another  mandrel  is  driven  through  it,  the  tube  being 
moist  will  cause  the  mandrel  to  rust  and  it  will  be  ruined  after 
having  been  used  but  a  few  times. 

The  next  step  is  to  take  the  mandrel  of  the  next  size  larger  than 
the  one  over  which  the  tube  was  first  rolled  and  drive  it  through  the 
tube,  having  the  tube  facing  towani  the  operator  and  the  surphis 
plate  extending  to  the  right.    The  end  of  the  tube  is  placed   on 


282 


TUBES  AND  SPLIT  PINS 


the  anvil  and   the  mandrel  driven  through  it  by  tapping  with  a 
light  hammer  until  it  comes  in  contact  with  the  anvil  (Fig.  511). 


Fig.  511 


The  mandrel  is  then  grasped  in  a  pin-vise  and  the  surplus  metal 
trimmed  away  as  close  to  the  tube  as  possible  (Fig.  512). 


THE  TUBES 


283 


The  mandrel  being  driven  thrc)U<:;li  in  this  manner,  with  tiie  lap 
to  the  rifiht.  allows  the  Hat  side  of  the  scissors  to  be  placed  a<iainst 
the  tnbe  and  thns  cnt  close  to  it.  The  lap  is  then  filed  perfectly 
smooth  and  flush  with  the  sides  of  the  tube  (Pig.  512,  aa),  so  that 
in  rotating  it  between  the  fingers,  no  unevenness  is  felt.  If  a  ridge 
is  felt  along  the  side,  it  should  be  filed  off  carefully  so  that  the 
diameter  is  no  greater  at  that  point  than  at  any  other. 


Fig.  512 


The  end  of  the  tube  is  then  bent  over  the  rounded  end  of  the 
mandrel  by  pressing  it  and  working  it  over  with  the  side  of  a  smooth, 
flat  file,  until  it  is  partially  closed  (Fig.  513).  The  stretching  of 
the  tube  over  the  mandrel  will  necessarily  make  it  fit  so  tightly 


Fig.  .51.3 


J'k;.   51  I 


that  it  cannot  be  jnilled  off,  but  by  rolling  it  a  little  under  a  smooth 
file  on  the  anvil,  with  a  little  pressure  the  metal  will  l)e  stretched 
sufficiently  to  allow  of  the  mandrel  being  removed. 

A  small  square  of  the  same  metal  of  which  the  tube  is  made 


284  TUBES  AND  SPLIT  PINS 

is  then  placed  on  the  charcoal  block  and  a  small  piece  of  pure 
gold  melted  on  its  surface.  The  tube  is  grasped  in  a  pair  of  pliers, 
the  partially  closed  end  being  down  and  resting  on  the  square 
of  the  platinum  (Fig.  514).  The  small  blue  flame  of  the  blow-pipe 
is  applied  and  as  the  pure  gold  melts  and  catches  the  tube  to  the 
floor  it  should  be  lifted  slightly  from  the  charcoal  block  so  as  to 
allow  a  flame  to  pass  underneath  the  floor  until  the  pure  gold  solder 
has  flowed  all  around,  perfectly  uniting  the  tube  to  the  floor.  The 
mandrel  is  again  driven  into  the  tube  and  placed  in  the  pin-vise, 
which  grasps  the  end  of  the  tube,  the  surplus  metal  of  the  floor 
is  cut  away  and  the  edges  filed  flush  with  the  sides  of  the  tube 
and  the  end  slightly  rounded. 

When  speaking  of  the  size  or  the  number  of  the  tube,  the  size  of 
the  mandrel  over  which  the  tube  was  finished  is  indicated.  Thus 
a  No.  4  tube  was  first  rolled  around  a  No.  3  mandrel  and  finished 
on  a  No.  4. 

The  No.  1  and  No.  2  tubes  are  indicated  in  the  teeth  having 
smaller  roots,  such  as  the  upper  laterals  and  bicuspids,  the  No.  2 
and  No.  3  for  the  upper  centrals  and  lower  bicuspids,  the  No.  3 
arid  No.  4  for  the  upper  centrals  and  upper  and  lower  cuspids  and 
No.  5  and  No.  6  for  the  molars. 

SPLIT  PINS. 

The  split  pin,  in  order  to  be  effective,  must  be  made  of  a  high 
fusing,  elastic  material  and  rigid  enough  to  withstand  the  strain 
to  which  it  will  be  subjected,  and  must  be  an  alloy  which  will  retain 
its  elasticity  even  after  being  subjected  to  a  very  high  heat. 

There  should  be  no  loss  of  metal  between  the  halves  to  weaken 
it  in  the  least,  and  it  should  have  practically  the  same  amount  of 
material  in  it  as  though  it  were  a  solid  pin.  The  solid  pin,  which 
has  been  sawn  through  the  center  in  order  to  produce  a  split  pin, 
is  worthless,  so  far  as  the  lasting  qualities  of  the  pin  goes,  for  the 
reason  that  a  saw  cut  made  through  the  center  of  the  metal,  has 
cut  it  away  at  its  strongest  part  and  rendered  it  very  weak  (Fig. 
515).  Half-round  wire  is  the  best  material  for  making  split  pins 
and  securing  a  maximum  amount  of  strength  (Fig.  516).  For  this 
purpose,  platinized  gold  or  clasp  wire  is  the  best. 

Iridio-platinum  Wire.— Iridio-platinum  wire,  while  it  may  be  a 
tougher  and  more  rigid  alloy  than  the  clasp  wire,  does  not  seem 
suitable  for  split  pins.     The  writer  did  considerable  experimenting 


SPLIT  PINS  285 

with  this  metal,  covering  a  period  of  two  or  three  years.  At  first 
it  seemed  as  though  this  was  the  metal  best  suited  for  the  making 
of  split  pins.  After  a  time,  however,  bridges  in  which  these  pins 
had  been  used  began  to  be  brought  to  him  with  the  pins  broken 


Fig.  515  Fig.  516 

close  up  to  the  caps  and  they  were  replaced  with  platinized  gold 
wire.  It  seemed  that  the  constant  springing  brought  about  a 
recrystallization  of  the  metal  which  rendered  it  very  brittle.  It 
would  break  with  a  clean  sharp  fracture,  showing  a  very  fine  grain 
which  jjresented  the  appearance  of  fractured  hardened  steel  as  of 
a  broken  needle.  This  result  followed  in  almost  every  case  where 
the  iridio-platinum  had  been  used,  so  that  its  use  was  finally 
discontinued. 

Platinized  Gold  or  Clasp  Wire. — Of  the  various  makes  of  gold  and 
platinum  alloys,  known  as  platinized  gold  or  clasp  wire,  which 
can  be  procured  from  the  different  dental  supply  houses,  very 
few  are  at  all  suitable  for  split  pins.  The  majority  are  too  soft, 
or  become  so  after  being  subjected  to  a  high  heat,  and  they  also 
have  too  low  a  fusing  point,  very  few  of  them  standing  a  higher 
heat  than  that  required  to  melt  18-carat  solder.  When  the  heat 
is  raised  above  this  point,  the  metal  loses  its  elasticity  and  is  apt 
to  be  fused  together. 

For  many  years  there  was  only  one  manufacturer  which  produced 
a  clasp  wire  which  was  suitable  for  this  purpose.  Within  the  past 
few  years,  however,  other  manufacturers  have  taken  the  matter  up 
and  it  is  now  possil)le  to  secure  other  makes  of  high-fusing  and  high- 
grade  metal  which  can  be  used.  It  should  have  a  melting  point 
above  that  of  coin  gold,  and  it  shoukl  be  possible  to  use  this  alloy 
as  a  solder  for  it  without  the  slightest  tendency  to  fuse,  and  without 
any  lo.ss  of  elasticity. 

During  a  scries  of  ex[)('rimerits  the  idea  of  sweating  tlic  halves 
together  was  tried,  but  the  i)rocess  proved  a  failure.  In  sweating  the 
parts  together,  the  whole  mass  of  metal  was  heated  nearly  to  the 
melting  i)oiiit  of  the  alloy  but  this  high  heat  brought  about  a  molec- 
ular chaiig«'  which  reiKiered  the  metal  practically  the  same  as  cast 


286  TUBES  AND  SPLIT  PINS 

gold,  with  the  result  that  the  pins  became  quite  brittle  and  were 
broken  in  a  comparatively  short  time,  necessitating  the  replacing 
of  them  in  nearly  every  instance  where  they  had  been  used. 

The  size  of  the  half-round  wire  used  in  making  the  pins  for  the 
different  sized  tubes,  will  run  from  about  No.  12  to  No.  14,  inclu- 
sive. The  wire  of  which  the  pin  is  to  be  made  should,  when  brought 
together,  be  of  a  slightly  greater  diameter  than  that  of  the  inside 
of  the  tube,  thus  giving  an  excess  sufficient  to  allow  for  turning  or 
filing  them  to  fit  the  tubes.  The  No.  14-gauge  wire  can  be  used 
for  the  No.  1  tube,  and  sometimes  for  the  No.  2,  the  No.  13-gauge 
for  the  No.  3  and  No.  4  and  No.  12-gauge  for  the  No.  5  and  No.  6. 
The  measurement  should  be  taken  from  the  bottom  of  the  tube 
to  the  floor  of  the  cap  and  the  wire  should  be  bent  about  one- 
eighth  of  an  inch  longer  so  that  the  pin  when  completed  will  stand 
that  distance  above  the  floor. 


Fig.  517 

The  half  round  wire  is  well  annealed  and  is  then  bent  on  itself, 
the  flat  side  innermost,  as  in  the  illustration  (Fig.  517).  It  is  then 
again  annealed  and  bent  still  further  over,  bringing  the  end  in 
contact  with  the  flat  surface  of  the  wire.  It  is  now  grasped  in  a 
pair  of  pliers,  at  point  a,  Fig.  518,  and  held  in  the  flame  of  a  Bunsen 
burner  until  it  reaches  a  red  heat.  The  ends  are  brought  together 
and  held  until  it  is  chilled  slightly,  thus  removing  the  spring  and 
bringing  the  ends  in  contact  for  about  one-eighth  of  an  inch.  The 
contact  should  be  long  enough  so  that  when  it  is  soldered  and  the 
pin  completed,  the  soldered  portion  will  come  beneath  the  floor 
of  the  cap.  The  pin  and  the  point  of  contact  is  longer  in  the  case 
of  an  inlay  and  tube  and  split  pin,  as  already  described. 

The  part  in  contact  is  then  fluxed  and  a  small  piece  of  coin  gold 
placed  on  the  flat  side  of  the  wire  in  contact  with  the  overlapping 
end,  point  b,  Fig.  518,  and  the  coin  gold  melted  with  the  blow- 
pipe and  drawn  through  sufficiently  to  unite  it.  Care  should 
be  takeii  not  to  use  an  excess  of  the  coin  gold  as  solder,  as 
by  so  doing  the  pin  may  be  very  materially  weakened.     If  a  large 


SPLIT  PINS 


28i 


amount  of  solder  has  been  used,  it  will  draw  through  into  the 
loop,  leaving  a  large  bulk  of  the  gold  extending  beyond  the  point  of 
contact  (Fig.  519,  a).  The  result  is  that  when  this  is  hammered 
or  forged  down,  so  that  the  two  sides  of  the  pin  are  in  contact,  the 
large  bulk  of  the  coin  gold  has  been  hammered  into  the  sides  of 
the  platinized  gold  wire,  so  that  both  sides  are  partially  cut  through, 
as  in  Fig.  520.  This  will,  of  course,  weaken  the  pin  at  this  point 
and  it  will  \ery  easily  be  broken. 

After  this  pin  has  been  soldered,  the  extending  wire  is  grasped 
in  the  pin-vise  and  the  sides  of  the  pin  hammered  together,  bring- 


FiG.  518 


Fig.  519 


ing  the  two  halves  in  contact.  During  the  hammering  or  forging 
the  pin  must  be  kept  rotating,  thus  forging  it  round  as  the  halVes 
are  gradually  brought  into  contact.  If  the  two  halves  are  ham- 
mered together  without  rotating,  it  will  be  found  that  the  sides 
have  been  flattened,  thus  making  the  diameter  of  the  pin  in  this 
direction  much  less  than  in  the  direction  of  the  split  (Fig.  521), 
This  will  render  it  much  more  difficult,  in  fact  it  will  be  almost 
impossible,  to  make  the  pin  perfectly  round,  whereas,  by  rotating 
it,  the  halves  are  brought  in  contact,  at  the  same  time  forging  it 
into  the  desired  shape  so  that  there  will  be  little  trouble  in  making 
the  pin  fit  the  tube.    After  forging,  the  pin  should  be  annealed. 


Fig.  520 


Fig.  521 


Filing  of  the  Pins. — Fihng  is  an  art.  There  may  be  some  who 
will  doubt  this  statement,  but  it  is  true  nevertheless.  To  learn 
to  use  a  file  properly  retpiires  a  great  deal  of  practice  and  some 
natural  ability,  and  before  inidertaking  to  fit  the  pin  to  a  tube, 
considerable  time  should  be  de\'oted  to  working  with  the  file. 
Of  as  great  importance  as  the  proj)er  use  of  the  file  is  the  jjroper 
method  of  using  the  pin-vise,  and  the  dentist  should  learn  to  rotate 
the  [)in-\is('  properly. 

Th<"  Ix'sl  |)in-vise  to  use  for  the  j)ur])(».se  is  one  which  is  perfectly 
round,  and  which  has  no  set  screws,  but  has  jaws  of  the  nature  of  a 


288 


TUBES  AND  SPLIT  PINS 


chuck  which  will  grasp  the  pin  and  hold  it  in  line  with  the  pin- vise. 
The  one  shown  in  the  illustration  (Fig.  522)  is  the  best  which  can 
be  procured  for  all  work  of  this  character. 

The  pin  is  grasped  by  the  soldered  end  in  the  pin-vise,  catching 
it  only  far  enough  down  to  get  a  strong  hold.  The  pin- vise  is  held 
lightly  in  the  fingers  of  the  left  hand,  the  end  of  the  thumb  resting 


Fig.  522 

on  the  top  of  the  pin-vise  and  the  pin  on  the  filing  block,  as  shown 
in  the  illustration  (Fig.  523). 

The  file  used  for  roughing  down  should  be  of  two  or  three  cut, 
flat,  and  about  five  inches  in  length,  and  should  be  held  in  the 
right  hand  very  lightly,  the  forefinger  resting  on  the  face  of  the 
file,  and  over  the  middle  of  the  pin  extending  from  the  pin-vise 


Fig.  523 


(Fig.  524).    The  pin- vise  is  then  rotated  to  the  right  with  the  thumb 
and  fingers  of  the  left  hand.     The  file  is  passed  lightly  over  the 


SPLIT  PINS 


289 


pill  in  the  opposite  direction,  very  little  pressure  being  used,  not 
much  more  than  the  weight  of  the  file  itself.  The  file  should  be 
moved  only  while  the  pin  is  rotating,  being  pushed  forward  over  the 
pin  and  lifted  from  it  while  the  pin-vise  is  still  in  motion.  If  this 
should  not  be  done,  and  when  the  pin  has  stopped  revolving,  the 
file  should  be  still  pushed  forward,  a  flat  surface  would  be  produced 
at  that  point.  As  previously  stated,  the  finger  should  rest  over  the 
middle  of  the  j)in  which  perhaps  extends  one-half  or  two-thirds  of 
the  way  across  the  file  (Fig.  524).    If  the  finger  is  held  at  the  outer 


Fig.  524 


edge  of  the  file,  there  will  be  a  greater  i)ressure  at  this  end  of  the 
l)in  than  there  should  be,  with  the  result  that  the  pin  will  be  made 
smaller  at  the  outer  end  and  the  sides  will  not  l)e])arallel  (Fig.  .")2r)). 
If  a  ver\-  short  j)in  is  being  filed,  the  finger  should  rest  at  the 
extreme  inside  edge  of  the  hie.  The  file  should  not  be  gras|)ed  as 
would  be  a  baseball  bat.  If  the  file  is  held  in  the  hand  ver\  lirnilv  , 
IJie  deliejite  sense  (»f  touch  is  lost  and  uneoiiseiousl.\-  a  greater 
pressure  is  |)lae<'d  on  one  or  the  other  end  of  the  pin,  with  tlu^ 
result  that  it  cannot  be  made  of  a  luiiform  diameter  throughout 
it-,  length.     When  the  file  is  held  very  lightly,  so  that  it  will  mo\e 


290 


TUBES  AND  SPLIT  PINS 


freely  with  the  slightest  pressure  of  the  forefinger,  it  will  find  its 
own  level  and  keep  the  sides  of  the  pin  parallel  from  one  end  to  the 
other. 


Fig.  525 

When  the  pin  has  been  roughed  down  with  the  coarse  file  to  nearly 
the  size  that  is  desired,  the  final  fitting  and  polishing  should  be  done 
with  the  finest  file  that  can  be  procured  and  afterward  it  is  burnished. 
For  the  final  finishing,  a  flat  file  about  five  inches  in  length  is 
used,  one  side  of  which  is  at  least  as  fine  as  a  six  cut,  and  better 
still  if  it  be  a  seven  or  eight  cut.  The  other  side  is  not  cut  at  all, 
but  is  perfectly  smooth  and  polished  for  use  as  a  burnisher. 

With  the  cut  side  of  the  file,  the  pin  is  smoothed  down  until  it 
is  very  nearly  as  it  should  be,  fitting  the  tube  snugly.  It  is  then 
burnished  with  the  smooth  side,  until  the  pin  becomes  perfectly 
smooth,  having  a  polished  surface  and  fitting  the  tube  easily 
throughout  its  entire  length. 

The  burnishing  is  perhaps  the  most  important  part  of  the  opera- 
tion of  making  a  split  pin,  for  the  reason  that  no  matter  how  fine 
the  file  which  is  used  in  fitting  the  pin  may  be,  it  leaves  a  surface, 
which,  under  the  microscope,  will  seem  to  be  very  rough,  the  serra- 
tions or  fine  ridges  and  grooves   presenting  the  appearance  of  a 


6 PUT  PINS 


291 


very  tine  thread  of  a  screw.  If  the  pin  should  he  used  without  any 
further  finishino;.  these  serrations,  being  so  \er\'  fine,  would  wear 
smooth  ver\'  quickly,  thus  reducing  the  size  of  the  pin  to  that 
extent  and  rendering  it  loose  in  the  tube  and  making  what  might 
be  termed  an  ill-fitting  or  loose-fitting  pin. 

Too  much  importance  cannot  be  placed  on  the  ])roper  fitting  of 
the  pin  into  the  tube.  The  pin  should  fit  the  tube  easily.  If  it 
fits  too  tightly,  it  would  be  difficult  when  the  bridge  is  waxed  in 
position  for  soldering  to  remo\e  the  outer  from  the  inner  parts 
without  springing  or  distorting  it,  and  it  would  also  require  too 
much  force  to  remove  the  briflge  from  the  mouth.  If  the  pin  goes 
into  the  tul)e  touching  the  sides  for  its  entire  length  it  may  fit 
easily,  so  that  it  will  slide  out  and  in  without  any  great  effort  to 
move  it. 

If  the  tube  is  very  long,  necessitating  a  split  pin  of  great  length, 
the  end  of  the  pin  can  remain  closed  and  at  any  future  time,  if  it 
should  be  necessary  to  spread  it  in  order  to  give  the  ])in  greater 
retenti\e  power,  it  can  be  opened  a  little  in  the  middle,  thus  making 
a  long,  narrow,  elliptic  spring  (Fig.  52G).  If  the  pin  is  short,  then  it 
is  filed  oj)en  at  the  end  and  the  end  carefully  rounded,  polished  and 
burnished. 

In  filing  it  oi)en  at  the  end,  the  file  should  follow  the  direction 
of  the  split  until  it  is  oi)en  (Fig.  527),  and  not  across  the  split.  The 
reason  for  this  is  that  in  filing  across  the  split,  as  soon  as  the  solid 


(D 


Fig.  520 


Fig.  527 


Fk;.  52.S 


end  is  filed  througii,  e\en  if  a  \<t\  fine  file  is  being  used,  the  farther 
half  of  the  pin  is  forced  awa.\  and  a  feather  edge  is  turned  o\-er 
on  the  far  side  of  the  inner  half  and  some  j)articles  of  the  filings 
may  Ix*  forced  between  the  halves,  thus  spreading  the  j)in  and 
making  it  difficuh  or  preventing  it  from  entering  the  tulx*  (Fig. 
r)2S).  This  would  necessitate  still  further  filing  ;ind  consefinent 
weakening  of  th<'  pin. 


292 


TUBES  AND  SPLIT  PINS 


THE   WEINSTEIN   DEVICES    FOR   MAKING    SPLIT    PINS. 

Mr.  L.  J.  Weinstein,  of  New  York,  has  invented  a  swaging  device 
to  assist  in  the  making  of  spHt  pins.  It  is  of  the  utmost  value,  and 
by  its  use  one  is  enabled  to  make  a  plit  pin  more  quickly  and  accur- 
ately than  is  possible  by  simply  forging  and  filing  (Fig.  529). 


Fig.  529 


Fig.  530 


The  device  consists  of  a  double  anvil,  octagonal  in  shape.  The 
two  halves  are  faced  off  so  that  there  is  perfect  contact  between 
the  two  faces,  and  these  are  guided  to,  and  held  in  their  proper 
positions  with  dowels.     From  each  of  the  octagonal  faces,  a  hole 


WEIXSTEIX   DEVICES   FOR   MAKING  SPLIT   PIXS        293 

is  (Irilli'd  toward  tlu-  ci'iitrr  Ix-twccn  the  liahos,  lca.\inu-  halt'  i-oiiiid 
grooves  of  ocpial  size  in  eacli  of  tlie  workinj;'  surfaces.  Tliese  have 
been  reamed  and  poHshed  and  the  sizes  of  the  holes  are  a  little 
more  than  one-thousandth  of  an  ineh  larger  than  the  mandrel 
corresponding  in  number  to  the  number  on  the  swager  (Fig.  530). 
The  half  round  wire  used  in  making  the  split  pins  is  a  little  more 
than  one  one-thousandth  of  an  ineh  larger  than  the  hole  in  the 
swager  in  which  it  is  to  be  finished.  A  draw  ])late  comes  with  the 
outfit,  the  numbers  corresponding  with  the  munbers  on  the  swager 
and  the  mandrels  (Fig.  531). 


Fig.  5.31 

Although  the  wire  ("elastic"  gold,  Weinstein's  formula)  may 
be  purchased  in  suitable  sizes,  thus  axoiding  the  necessity  of  draw- 
ing, it  is  well  to  have  the  draw  plate  in  ca.se  of  emergency,  as  it  is 
essential  that  the  size  of  the  wire  u.sed  should  correspond  with  the 
pin  it  is  desired  to  make. 

Fig.  532  shows  a  small  drawing  machine  invented  by  Dr.  (\  F. 
('.  Mehlig,  of  New  York,  for  drawing  wire  and  tubes.  It  is  a 
wonderful  little  machine,  and  is  geared  so  that  a  heavy  wire  can 
be  drawn  down  with  almost  no  effort. 

Making  the  Split  Pin. — The  wire,  of  a  number  corresponding  to 
the  number  of  the  nuuidrel  over  which  the  tube  has  been  made,  is 
bent  upon  itself,  brought  in  contact  as  shown  in  Figs.  517  and 
518,  and  .soldered  with  coin  gold.  The  extending  end  is  then 
grasped  in  the  pin-vise,  the  looped  end  placed  in  the  groove  on  the 
top  of  the  anvil  (Fig.  5.']3),  and  the  two  halves  l)roiiglit  in  contact 
with  a  small  co[)per  or  fiber  faced  hammer. 

In  order  to  bring  the  two  halves  of  the  pin  into  perfect  contact, 
prior  to  the  final  forging,  the  pin  is  first  |)laced  into  the  swager, 
with  the  split  Ixing  horizontally,  and  struck  once  w  ith  a  good  sharp 
blow.  If  the  pin  is  to  be.  for  exairi])lc,  a  number  .1.  the  closing  is 
to  be  done  in  the  nund»cr  '.'>  hole    .\ftcr  the  pin  is  closed,  it  is  then 


294 


TUBES  AND  SPLIT  PINS 


annealed  and  first  swaged  in  number  5  hole  and  hammered  with  a 
heavy  round-faced  rawhide,  or  fiber-faced  mallet,  rotating  the  pin 
constantly  until  the  two  faces  of  the  anvil  are  in  contact.     (Siee 


•«t 


Fig.  532 


Fig.  533 


Fig.  534.)  It  is  then  annealed  and  hammered  in  the  number  4  hole, 
then  in  the  number  3  hole,  and  when  the  two  faces  of  the  swager 
are  in  contact,  the  pin  is  quite  round,  the  sides  are  parallel,  and  it  is 
slightly  larger  than  the  tube,  just  enough  to  allow  for  finishing.     It  is 


WEIXSTEIX   DEVICES  FOR  MAKING  SPLIT  PINS       295 


Fig.  534 


m 


I'KJ.  .Vi') 


296 


TUBES  AND  SPLIT  PINS 


then  annealed  again  and  finished  with  a  fine  file  and  a  bnrnisher 
as  has  been  described  or  it  can  be  burnished  on  the  lathe. 

Finishing  the  Split  Pin  on  the  Lathe.^ — It  is  necessary  to  have  a 
chuck  of  suitable  size  and  kind  to  grasp  the  pin  firmly.  It  is  then 
brought  down  with  a  very  fine  file  until  it  will  just  enter  the  tube 
tightly.  The  filing  can  be  done  more  easily  and  perfectly  if  the 
under  surface  is  supported  by  a  very  fine  file  on  an  instrument  with 
a  smooth  flat  surface,  as  shown  in  Fig.  535.  The  burnishing  is 
done  with  another  device  of  ]Mr.  Weinstein's,  which  consists  of  two 
hinged,  hardened,  and  polished  plates,  one  of  which  is  grooved  to 
receive  the  pin  (Fig.  536).     The  two  plates  are  brought  together, 


Fig.  536 


the  lathe  run  at  full  speed,  the  burnisher  being  moved  outward 
and  inward  on  the  pin  (Fig.  537),  this  giving  it  a  smooth  and 
highly  polished  surface. 

While  still  in  the  lathe  chuck,  it  is  polished  with  fine  crocus  cloth 
and  reburnished.  The  pin  is  then  opened  at  the  end,  and  rounded 
in  the  manner  already  described  (Fig.  527)  or  left  closed  in  a  long 
pin.     (See  Fig.  526.) 

The  split-pin  swager  illustrated  was  originally  made  with  eight 


ANOTHER  METHOD  OF   USING   TUBE  AND  SPLIT  PIN      297 

grooves  hotwrni  the  two  halves  to  pr()\i(K>  for  the  six  i)ins  accord- 
ing to  the  stul)  steel  luaiulrel  sizes,  .():)S  inch  to  .OTf)  iiicli.  and 
two  extra  ii;rooves  for  the  ])reliininary  swa.uiiig  (of  No.  (i  pin),  it 
has  l)een  found  advisal)le,  however,  to  reduce  the  number  of  the 


Vir..  .-,;J7 

grooves,  mandrels,  etc.,  for  l)oth  the  swaging  device  and  paralleling 
device  and  the  various  accessories  and  the  completed  device,  both 
for  paralleling  and  swaging  now  furnished  are  standardized  for 
four  sizes,  as  follows:  No.  1  equals  O.OfiO  inch;  No.  2,  0.004  inch; 
No.  3,  0.068  inch,  and  No.  4,  0.072  inch. 

The  split-pin  swager,  burnishing  clamp,  fiber-faced  mallet,  draw 
plates  for  l)oth  wire  and  tubing  and  accessories,  such  as  files,  etc., 
are  manufactured  by  the  Dental  Ftilities  Co.,  of  New  York. 


ANOTHER   METHOD   OF   USING    THE   TUBE   AND   SPLIT   PIN. 

There  are  cases  where  the  ordinary  way  of  using  the  tube  in  th<; 
root  with  the  split  pin  attached  to  the  bridge  is  not  i)ractical  and 
it  is  necessary  to  devise  some  other  method.  In  some  eases  a 
eom|)lete  re\<TsaI  of  this  type  of  attachmenl  is  indicated,  using  1  he 


298  TUBjEIS  ANb  SPLIT  PINS 

split  pin  on  the  inner  cap  attached  to  the  root,  while  the  tube 
is  imbedded  in  the  bridge.  There  are  times  where  the  roots  stand 
on  such  divergent  angles  that  it  is  not  possible  to  insert  tubes  to 
a  sufficient  depth  to  give  retention  and  have  them  parallel,  and 
it  is  in  such  cases  that  the  reversal  of  order  is  more  frequently 
indicated.  Take  for  example  two  cuspid  teeth  in  the  lower  jaw, 
standing  as  represented  in  Fig.  538. 

In  a  case  of  this  description,  the  roots  are  prepared  in  the  same 
manner  as  when  they  stand  in  a  normal  position,  with  the  exception 


Fig.  538  Fig.  539 

that  the  mesial  or  approximal  sides  are  cut  well  away,  as  in  Fig. 
539,  in  order  that  the  bands  may  be  adjusted  with  their  sides  nearly 
parallel  to  each  other.  The  labial  and  lingual  sides  are  trimmed, 
but  it  will  not  be  necessary  to  trim  the  distal  sides,  as  the  inclina- 
tion of  the  roots  is  such  that  the  band  will  hug  tightly  at  these 
points. 

The  bands  are  then  fitted,  the  roots  cut  down  to  their  proper 
level,  and  the  canals  enlarged  to  receive  a  strong  post.  Posts  are 
then  placed  in  the  canals,  extending  well  above  the  bands  and  a 
plaster  impression  taken  with  bands  and  posts  in  position  as  in 
Fig.  540. 

A  model  is  then  made  and  the  work  from  here  on  is  done  entirely 
on  this.  The  bands  cut  flush  with  the  top  of  the  stump  and  the 
floor  of  No.  28-gauge  coin  gold  is  sweated  to  them. 

The  pins  are  made  from  half  round  platinized  gold  wire,  the  same 
as  the  ordinary  split  pin,  and  being  soldered  for  about  three-eighths 
to  one-half  an  inch,  leaving  them  open  for  about  one-quarter  of  an 
inch  from  the  upper  end.  The  pins  are  then  fitted  to  the  tubes 
which  have  previously  been  made  and  should  be  of  about  a  No.  3 
or  No,  4. 

Openings  are  then  made  through  the  floors  of  the  caps  to  fit  the 
pins  tightly  and  the  floors  polished.  The  upper  ends  of  the  pins  are 
then  grasped  in  the  pin-vise  so  that  they  are  clutched  just  below 


ANOTHER  METHOD  Ol<'  iSlX'U  TlbE  AND  SPLIT  PIN     299 

the  point  \\lu're  tliey  are  soldered  and  are  bent  so  that  the  l)end 
will  come  just  beneath  the  floor  and  wlien  they  jiass  through  the 
floor  the>'  will  stand  parallel  with  each  other  (Fig.  541). 


Fig.  .540 


Fui.  .541 


A  little  wax  is  placed  around  the  pins  where  they  pass 
through  the  floors,  the  wax  being  very  hot  and  afterward  every 
particle  of  wax  should  be  scraped  from  around  the  pin  and  oft' 
the  floor  so  that  no  solder  may  draw  through  at  this  point.  A 
little  impression  is  then  taken,  in  investment  material,  of  each  of 
the  caps  with  the  pins  in  place.  The  caps  and  pins  will  probably 
come  away  with  the  impression.  If  not,  they  are  removed  from 
the  stumps  and  carefully  placed  in  the  impression.  The  investment 
impressions  are  dried  out,  the  pins  fluxed  on  the  inside  of  the  caps 
where  they  pass  through  the  floors  and  they  are  soldered  to  the 
floors  from  the  inside  with  2()-carat  solder,  as  shown  in  Fig.  544. 


Vic.  .542 


Fi(i.  .54.S 


Fi<;.  .541 


They  are  thus  soldcrcrl  from  the  inside,  so  that  no  solder  ma\' 
flow  on  the  outside  of  the  floors  of  the  ca])s  or  around  the  pins  and 
thus  interfere  with  the  fit  of  the  tubes  and  outer  caps. 

Making  the  Outer  Cap.  In  making  an  outer  cap  for  this  style  of 
abutment,  a  floor  of  No.  2S-gaugc  coin  gold  is  used  and  the  hole 
is  made  so  as  to  fit  the  pin  easily,  but  not  loosely.  It  is  then  cut 
flush  with  the  sides  of  tlw  inner  cap  and  tin-  lialf-band  fitted  to  it 
and  soldered  as  in  tlic  making  of  a  caj)  of  the  regular  txpe,  after 
wliicli  it  is  replaecd  on  tlic  inner  cap  (Fig.  54;i). 

Tlic  tube,  uliich  -^lioiild  be  the  exact  length  of  tlic  pin  and  close<l 


300  TUBES  AND  SPLIT  PINS 

at  the  upper  end,  is  next  placed  over  the  pin  and  is  made  so  that  it 
will  set  down  closely  to  the  floor  all  around  and  is  waxed  to  it  with 
a  hard  tough  Avax.  It  is  then  removed,  a  little  investing  material 
carried  into  the  tube  and  a  small  iron  wire  inserted,  letting  it  extend 
about  one-quarter  of  an  inch  below  the  floor,  as  in  Fig.  544.  This 
will  hold  the  tube  in  place  so  that  it  will  be  impossible  for  it  to  shift 
its  position  and  it  is  imbedded  in  the  investment  (Fig.  545).  The 
tube  is  soldered  to  the  floor  with  21-  or  22-carat  solder. 

After  cleansing  and  drying  the  facing  is  ground  to  the  floor  of 
this  cap  (Fig.  546)  and  when  the  bridge  is  invested  for  soldering, 
a  small  wire  is  inserted  into  the  tube  and  imbedded  in  the  invest- 
ment the  same  as  when  attaching  it  to  the  floor,  to  prevent  it  from 
shifting. 


Fig.  54.5  Fig.  546  Fig.  547 

In  soldering  this  crown,  it  is  necessary  that  the  tube  should  be 
completely  imbedded  in  and  entirely  covered  with  the  solder  which 
should  be  of  20  carat.  It  is  rarely  that  the  proper  lingual  contour 
of  a  cuspid  crown  of  this  type  can  be  obtained  as  the  tube  is  of  such 
bulk  and  must  have  sufficient  length  to  give  it  retention,  so  that  the 
crown  will  necessarily  be  bulky  on  the  lingual  side  (Fig.  547), 
often  presenting  something  the  appearance  of  a  lower  first 
bicuspid. 

These  crowns  may  at  times  be  used  in  any  of  the  teeth  anterior 
to  the  molars  and  form  practically  as  good  an  anchorage  as  a  crown 
of  the  regular  type,  but  as  they  are  more  difficult  to  make  they 
are  not  used  except  where  especially  indicated. 

In  cementing  these  caps,  it  is  not  possible  to  cement  them  in  the 
way  in  which  the  caps  of  removable  bridges  are  ordinarily  cemented, 
as  the  inclination  of  the  pins  is  such  that  they  could  not  enter  the 
roots.  In  this  type  it  will  be  necessary  to  set  the  crowns  separately, 
using  only  as  much  cement  as  is  required  to  set  them  properly  and 
then  placing  the  bridge  over  them  immediately,  before  the  cement 
has  had  time  to  set,  thus  insuring  their  being  perfectly  seated  in 
their  proper  position.  The  outer  caps  should  be  coated  with  cocoa- 
butter  so  that  if  a  little  of  the  cement  should  get  between  the  outer 
and  inner  caps,  they  could  be  readily  separated. 


CHAPTER  XIV. 

METHODS  OF  USING  PORCELAIN  CROWNS  WITH  CAST 
BASES  IN  REMOVABLE  BRIDGE-WORK. 

With  the  ad\ent  of  the  casting  process,  came  the  more  general 
use  of  all  porcelain  crowns  for  bridge-work,  in  place  of  the  facings 
or  veneers  which  had  heretofore  been  used  to  partially  hide  the 
mass  of  gold  of  which  the  bridge  proper  was  constructed,  thus 
producing  much  more  artistic  effects  than  was  possible  by  the  old 
methods. 

The  casting  process,  however,  has  its  limitations,  and  is  very 
far  from  being  a  "cure-all"  for  everything.  There  are  far  fewer 
cases  where  this  process  is  really  indicated  than  many  seem  to 
think.  Those  who  expected  to  use  it  to  the  exclusion  of  every 
other  method  have  doubtless  found  themselves  badly  mistaken. 

In  long  bridges,  where  great  strength  and  stability  are  essential, 
the  casting  process  is  not  indicated,  as  the  cast  bridge  is  far  inferior 
in  strength  to  a  soldered  l)ridge,  and  the  shrinkage  of  a  large  piece 
in  casting  is  such  as  to  render  it  unsuital)le  where  great  accuracy 
is  required.  In  some  instances,  it  is  much  more  suitable  for  fixed 
bridges  than  removable,  and  then  again,  the  rex'crse  mav  be  true. 
Good  judgment  nnist  be  used  in  its  application,  and  it  must  be 
used  only  where  indicated  to  avoid  disappointment. 

In  a  large  number  of  instances,  the  casting  ])rocess  may  l)e  used 
for  certain  parts  of  the  work,  but  it  is  very  rarely  that  it  should 
be  used  throughout  the  whole  operation. 

The  dcj)th  of  the  })ite  is  a  ver\'  essential  factor  in  using  jxjrcelain 
crowns  in  bridge-work.  This  nnist  be  great  enough  to  allow  suffi- 
cient room  for  a  good  substantial  base  in  order  to  gi\'e  strength 
and  stability  to  the  bridge.  A  very  close  bite  is  altogether  unsuit- 
able for  the  use  of  crowns,  and  where  we  ha\'e  this  eonditicui,  we 
must  resort  to  the  older  niethods  In  order  (o  produce  results  which 
will  be  satisfactory  and  <lurable. 

I'oreelain  crowns  are  especially  ap|>li<iil»le  in  (lie  anlerior  part  of 
the  mouth,  as  all  i)orcelain  crowns  present  a  nuich  more  life-like 
an<l  natural  aj)i)earancc  than  does  a  facing  which   is  backed  with 


302    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

metal,  although  there  are  many  cases  where  it  is  impossible  to  get 
shades  which  will  answer  the  purpose.  The  incisal  edges  of -the 
teeth,  especially,  are  frequently  lacking  in  that  clear  translucency 
which  is  to  be  noticed  in  most  of  the  natural  teeth,  and  it  is  often 
necessary  to  resort  to  the  backed  facings,  even  when  making 
restorations  in  the  posterior  part  of  the  mouth,  but  the  bicuspids 
and  molars  are  much  more  easily  matched  than  are  the  incisors. 

In  making  a  bridge  of  this  character,  the  crowns  of  any  of  the 
diflPerent  manufacturers  which  come  nearest,  in  mould,  shade, 
and  texture,  to  the  requirements  of  the  case  may  be  used.  There 
must  be  a  sufficient  depth  of  bite  to  allow  of  every  crown  having  a 
base  deep  enough  to  give  strength  and  stability  to  the  bridge. 

It  would  be  well  to  first  consider  a  bridge  for  the  anterior  part 
of  the  mouth,  restoring  the  six  anterior  teeth,  using  the  cuspid 
roots  as  abutments.  The  caps,  together  with  the  tubes  and  split 
pins,  are  made  as  has  been  previously  described,  and  an  impression 
for  the  saddle  taken,  the  model  and  dies  prepared,  and  the  saddle 
swaged  of  No.  32-gauge  soft  platinum.  Unless  the  bite  is  extremely 
long,  and  there  has  been  considerable  resorption,  the  saddle  should 
extend  only  to  about  half  or  two-thirds  of  the  way  over  the  ridge 
labially,  as  at  least  one-third  of  the  base  of  the  crowns,  labially, 
should  be  made  to  fit  closely  on  the  ridge.  The  saddle  is  reinforced, 
with  coin  gold,  adjusted  to  the  ridge  and  the  relation  of  the  saddle 
to  the  caps  taken  with  the  saddle  under  pressure.  The  impression 
and  bite  being  taken  together. 

The  model  is  then  prepared  and  the  crowns  are  ground  in  posi- 
tion. The  cuspid  crowns  should  first  be  fitted  and  ground  so  as  to 
touch  the  labial  third  of  the  floor  of  the  outer  caps,  clearing  enough 
lingually  to  afford  a  strong  base  and  the  lingual  and  mesial  sides 
are  beveled,  as  in  the  case  of  single  crowns  in  Fig.  548. 


Fig.  548 


The  incisor  crowns  are  then  ground  in,  the  model  having  been 
scraped  somewhat  to  allow  of  their  setting  closely  against  the 


MAKING   THE  BASES  303 

gum  when  the  bridge  i-;  completed.  They  sliould  fit  the  plaster 
model  on  the  labial  side,  but  should  be  ground  to  clear  the  saddle 
well  lingually,  so  as  to  get  a  sufficient  depth  of  metal  for  strength, 
as  in  Fig.  549. 

The  lingual  and  mesial  and  distal  sides  of  the  base  of  the  crowns 
are  then  beveled  the  same  as  the  cuspid  crowns  have  been,  and 
after  the  crowns  have  all  been  arranged  in  a  satisfactory  manner, 
they  are  waxed  in  place. 

Making  the  Bases. — In  a  large  number  of  bridges  of  this  character, 
which  are  made  for  the  anterior  part  of  the  mouth,  it  will  be  found 
that  the  lingual  contour  of  the  crowns  is  not  sufficient  to  give  the 
necessary  strength  after  they  have  been  ground  in  position,  and 
where  such  is  the  case,  it  is  necessary  to  first  build  them  up  on  the 


J'iG.  .550  Fig.  5.51 

lingual  sides  before  grinding  (Fig.  550).  This  is  especially  true  of 
the  crowns  made  by  some  manufacturers.  If  the  base  of  the  crowns 
are  ground  away  lingually  as  much  as  is  necessary,  it  will  leave 
practically  no  hold  for  the  post,  and  very  little  bulk  of  i)()rcelain 
back  of  it  to  give  the  necessary  strength  to  the  crown,  as  will  be 
seen  in  the  illustration  (Fig.  551).  It  will  also  decrease  the  labial 
lingual  de})th  of  the  base  of  the  crown  by  about  one-third.  This 
will  apply  both  to  the  cuspids  and  to  the  incisors,  and  it  is  very 
rarely  that  the  writer  uses  these  crowns  without  first  building  out 
the  contour  considerably  in  porcelain  on  the  lingual  side  before 
grinding.  Then,  too,  the  shapes  of  the  cuspid  crowns  are  scarcely 
ever  normal,  the  lingual  surface  being  decidedly  concave  and 
more  the  shape  of  an  incisor,  while  it  should  be  thick  and  heavy, 
as  shown  in  Fig.  552,  indeed  often  being  slightly  convex  rather 
than  concave. 

The  enamel  on  the  lingual  side  of  the  crown  should  be  first 
ground  away  with  a  fine  carborundum  or  an  emery  disk,  so  as 
to  afl'ord  a  better  attaehment  for  the  j)oneluin  which  is  to  l)e 
baked  on.  The  ponclain  is  then  built  in  lieavil\-,  us  in  Fig.  510, 
enough  being  added  so  that  when  the  base  of  the  crown  is  ground 
away,  as  in    Figs.  5  IS  mikI   510,  the   labial  and    lingual   diameter 


304    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

is  great  enough  to  cover  the  entire  cuspid  cap,  and  in  the  incisors 
so  that  after  grinding,  the  Ungual  side  will  be  extended  so  that  the 
pin  will  come  up  near  the  center  of  the  crown  or,  better  still,  a  little 
labially,  the  bulk  of  the  porcelain  being  on  the  lingual  side. 

After  the  crowns  are  properly  ground,  it  will  generally  be  found 

that  the  post-holes  are  too   shallow  to  give   support  and   they 

should  be  deepened  enough  to  allow  of  the  use  of  a 

post  of  sufficient  length  to  give  ample  support.     This 

may  be  done  by  using  a  copper  wire  in  the  engine  and 

deepening  the  hole  in  the    crown  with  carborundum. 

Carborundum  and  oil  may  be  used,  or  what  is  still  better 

powdered    carborundum    and   glycerine,    the   glycerine 

forming  a  good  vehicle  for  carrying  the  powder,  and 

at  the  same  time  being  much  more  easily  washed  away, 

as  the  glycerine,  mixing  freely  with  water,  will  permit  of 

Fig.  552      the  cavity  being  washed  out  quickly  with  clear  water, 

while  in  using  the  oil  for  carrying  the  carborundum, 

which  will  cut  no  better  than  glycerine  mixture,  it  is  necessary  to 

wash  thoroughly  with  soap  and  water. 

Making  Copper  Drills. — Copper  drills  are  easily  made.  A  piece 
of  wire  of  the  same  size  and  of  about  the  same  length  as  the  shank 
of  the  engine  burs  is  .secured  and  one  end  ground  or  turned  down, 
for  about  one-half  an  inch,  to  the  size  which  the  holes  in  the  crown 
are  intended  to  be.  They  are  then  placed  in  the  hand-piece  and 
used  in  the  same  manner  as  an  engine  drill. 

The  point  of  the  copper  drill  is  dipped  into  the  carborundum 
and  glycerine  and  entered  into  the  hole  in  the  crown  and  the  engine 
run  rapidly,  the  point  of  the  drill  being  moved  up  and  down  so  as 
to  keep  the  carborundum  and  glycerine  constantly  in  the  bottom 
of  the  cavity.  This  should  be  continued  until  the  cavity  is  of  a 
sufficient  depth.  The  end  of  the  drill  should  be  perfectly  flat, 
or  still  better  slightly  countersunk,  so  that  it  is  enabled  to  hold 
the  grinding  powder  better.  It  may  be  countersunk  by  running  it 
rapidly  and  holding  the  end  against  the  end  of  a  small  drill  or  bur. 
A  number  of  these  drills  may  be  made  and  kept  on  hand  and 
recountersunk  from  time  to  time  as  the  ends  become  rounded,  for 
when  the  drills  are  so  worn  they  do  not  work  well,  the  carborundum 
and  glycerhie  working  on  the  side  rather  than  at  the  point  of 
the  drill. 

The  crowns  being  finally  ground  in  position,  a  wall  of  plaster  is 
built  up  on  the  labial  side,  extending  to  within  a  thirty-second  or 


.l/.lA7.Vf,'  COPPER   DlilLLS 


:;():) 


a  sixteenth  of  an  ineli  of  the  ineisal  ed,i;e,  as  in  Fig.  053.    Tlie  next 
step  is  bnikling  np  of  the  bases  in  wax,  preparatory  to  casting. 


Fig.  553 


The  greatest  difficulty  with  which  the  operator  lias  to  contend 
in  making  these  bases  is  due  to  the  contraction  of  the  cast  metal 
on  cooling.  The  result  is  that  the  crowns  do  not  fit  as  they  should, 
and  there  is  more  or  less  cutting,  trimming  and  fitting  to  do,  before 
they  will  go  in  place,  and  not  infrequently  it  is  even  necessary  to 
do  the  work  over  again,  and  perhaps  even  then  the  desired  result 
will  not  be  attained. 

The  method  has  been  tried  of  first  burnishing  or  swaging  pure 
gold  over  the  bases* of  the  crowns  and  then  waxing  up  and  casting 
on  to  the  pure  gold.  This  has  perhaps  improved  the  matter  some- 
what, but  still  it  is  very  rarely  that  it  has  been  possible  to  secure 
anything  like  a  perfectly-fitting  base,  especially  if  the  crowns  are 
of  an\'  considerable  size,  for  with  the  hirger  castings  there  is  a 
proportionately  greater  amount  of  shrinkage. 

One  method  of  overcoming  tliis  difficulty  is  that  of  building  out, 
or  cnhuging,  the  base  of  the  crown  before  waxing,  in  order  to  make 
up  for  the  shrinkage  of  gold.  After  some  experimenting,  a  ])hin 
was  devised,  which,  while  not  entirely  overcoming  the  difficulty 
in  every  instance,  probably  due  to  faulty  technic,  has,  in  the 
majority  of  cases  reduced  the  trouble  to  a  mininnnn.  The  method 
floes  not  do  away  with  the  shrinkage  of  the  gold,  for  that  is  an 
inherent  property  which  nothing  can  overcome,  but  by  it  the 
o[)erator  may  counteract  or  make  allowiiiice  for  this  contniction 
of  the  metal  on  cooling. 

Tin;   method   of  procedure   is  as  Inilows:     Tin    foil,   of   \arying 
thicknesses,  according  to  the  si/e  (»f  the  crown  which  is  to  be  used, 
is  burnished  or  swaged  over  the  crown  base,  in  rcidity  first  making 
20 


306    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

a  base  of  this  metal,  letting  it  extend  just  a  little  above  the  beveled 
edge  of  the  crown,  as  in  Figs.  554  and  564. 

The  tin  foil  base  is  then  lubricated  with  cocoa-butter,  and  the 
wax  base  is  built  over  the  tin  foil,  the  lubricated  surface  allowing 
of  its  easy  removal.  The  size  of  the  base  of  the  crown 
has,  of  course,  been  increased  the  amount  of  the  thickness 
of  the  tin.  Allowance  for  the  shrinkage  has  thus  been 
made  so  that  when,  the  crown  is  placed  in  the  casting 
Fig.  554  it  fits  vcF}^  closely,  and  if  the  technic  has  been  carefully 
carried  out  there  will  be  little  or  no  trimming  to  be  done 
after  casting.  The  thickness  of  the  tin  foil  is  varied  according  to 
the  size  of  the  crown,  the  largest  of  course  requiring  the  heaviest 
foil.  Three  sizes  are  used,  the  first  being  about  .004,  the  second 
.006,  and  the  third  .008  of  an  inch  in  thickness.  The  burnishing 
of  the  foil  over  the  bases  is  very  quickly  and  easily  done.  The 
lighter  foil  can  be  pressed  nearly  to  place  with  a  piece  of  soft  rubber 
and  the  wrinkles  at  the  edges  smoothed  out  with  the  thumb  nail 
or  a  piece  of  orange  wood.  With  the  heavier  foils  a  piece  of  orange- 
wood  and  a  small  burnisher  are  all  that  are  required  to  secure  the 
close  adaption  which  is  necessary  to  insure  a  perfect-fitting  base. 

In  making  the  bases  for  a  series  of  crowns  for  a  bridge,  it  is  not 
advisable  to  cast  them  together  in  one  piece.  The  obvious  reason 
for  this  is  that  if  the  bridge  be  of  any  considerable  length,  the 
shrinkage  would  be  proportionately  greater  in  that  direction,  so 
that  it  would  be  necessary  to  grind  the  crowns  on  their  approximal 
surfaces,  before  they  would  go  into  position  on  their  bases.  This 
would  result  in  shortening  the  body  of  the  bridge,  and  leaving  a 
space  at  the  extremities  between  the  crowns  and  the  adjoining 
teeth  or  the  abutments.  The  best  method  is  to  cast  the  bases  sepa- 
rately, and  in  no  instance  should  more  than  two  bases  be  cast 
together.  The  casting  of  each  base  separately,  and  afterward 
uniting  them  does  away  with  the  shrinkage  which  would  otherwise 
take  place. 

The  casting  of  the  bases  for  abutment  crowns  may  be  done 
directly  on  the  caps,  or  they  may  be  cast  separately  and  afterward 
soldered  to  the  caps,  and  the  operator  may  choose  whichever  manner 
he  wishes,  although  the  latter  method  is  perhaps  preferable  at 
times  in  removable  work,  as  there  is  less  danger  of  disturbing  the 
accuracy  of  adjustment  between  the  outer  and  the  inner  caps. 

The  same  method  of  procedure  obtains  where  a  saddle  is  used 
as  an  auxiliary  support  to  the  abutments  and  the  crowns  mounted 


MAKING  COPPER  DRILLS  ;5()7 

on  this  saddle.  If  the  saddle  is  small,  as  it  would  be  in  the  case  of 
a  restoration  of  a  single  tooth,  and  if  there  is  not  great  depth  between 
the  occluding  teeth  and  the  saddle,  the  crowns  are  ground  so  as  to 
leave  sufficient  space  for  the  base  (Fig.  555)  and  then  be\eled  as 
in  shown  Figs.  555  and  556.   The  crowns  are  tinned  and  lubricated  in 


!•  iG.  .55.5  Fig.  o56  Fig.  557  Fig.  558 

the  manner  described,  but  the  saddle  is  left  perfectly  dry  and  clean. 
The  wax  is  then  flowed  between  the  bases  and  the  saddle  and  care- 
fully car\-ed  to  represent  the  gum.  The  sprue  wire  is  attached  to 
the  lingual  side,  and  the  crowns  are  remo^•ed  from  their  bases 
as  in  Figs.  557  and  558.  A  little  space  on  the  sides  of  the  saddle 
is  left  exposed  and  free  from  wax  so  that  it  may  be  caught  and  held 
firndy  in  the  investment  for  casting.  After  investing,  it  is  cast 
in  the  usual  manner  with  coin  gold. 

After  the  casting  has  been  made  and  cleansed,  it  is  waxed  to  the 
abutment  cap  or  caps,  as  the  case  ma\'  })e,  and  invested  prepara- 
tory- to  soldering  the  base  and  saddle  to  the  cai)s.  The  inside  of 
the  bases  are  well  c()\ere(l  with  whiting  so  that  no  solder  may  flow 
in  and  destroy  the  fit  of  the  crowns.  The  piece  is  then  heated  up 
and  soldered  with  20-  or  21-carat  solder.  Where  the  bases  are  cast 
separately  and  afterward  soldered  to  the  saddle  or  the  caps,  both 
the  saddle  or  caps  and  the  tinned  base  of  the  crowns  are  first  lubri- 
cated. A  little  of  the  inlay  wax  is  then  pressed  into  the  hole  in  the 
base  of  the  crown  to  serve  as  a  post  and  trimmed  off  so  that  it  is 
only  a  little  more  than  flush  with  the  base. 

The  crown  is  held  in  position  on  the  model  b\-  the  wall  which 
is  made  for  this  purpose,  and  the  inlay  wax  is  flowed  over  the  caps 
or  the  saddle  between  it  and  the  crown.  The  wax  should  be  used 
(juite  hot  so  that  it  will  attach  itself  to  the  wax  post  in  the  base. 
The  space  between  the  cap  and  base  is  well  filled  in,  leaving  it 
perhaps  a  little  more  than  flush  with  the  sides  of  the  crown,  covering 
the  beveled  edges  well.  It  is  then  carved  and  the  sprue  wire 
attached  to  the  lingual  si<lc.     The  crown  is  then  carefulh'  lifted 


308    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

away  from  the  wax  base  and  the  wax  base  removed  from  the  cap 
or  saddle. 

Before  waxing,  it  is  well  to  make  a  couple  of  little  pits  or  slight 
grooves  at  different  parts  on  the  cap  or  saddle  so  that  when  the 
base  is  cast,  it  will  be  positively  seated  in  its  proper  place  (Fig.  559). 
On  the  cap  a  slight  countersink  with  a  bur  or  drill  may  be  made  in 
the  top  of  the  post  and  another  at  some  point  near  to  it  and  on  the 
saddle  at  any  place  where  the  platinum  has  been  covered  with  coin 
gold.  After  the  bases  have  been  cast  and  cleansed,  they  are  adjusted 
in  position  on  the  saddle  or  caps,  and  invested,  being  held  in  place 
by  a  little  wire  clamp.  The  top  of  the  post  is  slightly  countersunk 
and  the  end  of  the  wire  clamp  is  pointed. 


Fig.  559  Fig.  560  Fig.  561 


In  the  case  of  a  saddle,  the  wire  clamp  extends  from  the  top  of 
the  post  to  the  under  part  of  the  saddle  directly  beneath  it,  just 
clearing  it  on  the  buccal  side,  as  shown  in  Fig.  560.  Where  the 
base  is  to  be  soldered  to  the  half  cap,  the  wire  extends  from  the  top 
of  the  post  to  the  under  part  of  the  floor,  and  as  nearly  on  a  line 
with  the  crown  post  as  possible,  as  shown  in  Fig.  561. 

The  investment  should  be  very  light  and  just  fill  the  under  side 
of  the  cap  or  saddle,  having  only  enough  to  hold  the  parts  in  posi- 
tion, leaving  the  whole  of  the  upper  parts  exposed.  This  facilitates 
the  thorough  heating-up  of  the  piece  and  the  solder  is  easily  drawn 
through  from  the  lingual  side,  uniting  the  bases  to  the  saddle  and 
to  each  other.  The  crown  side  of  the  bases  should  be  well  coated 
with  whiting  or  some  antiflux,  so  that  there  is  no  danger  of  the 
solder  flowing  over  this  surface. 

The  solder  is  used  in  strips,  and  is  fed  from  points  a  in  Figs. 
560  and  561.  The  invested  pieces  are  heated  up  very  highly  and 
the  solder  drawn  entirely  through  from  these  points.  It  may  be 
flushed  over  the  lingual  sides  as  much  as  is  required.  Twenty  or 
21 -carat  solder  is  used  for  this  purpose,  but  the  21 -carat  is  to  be 
preferred,  as  it  is  not  likely  to  be  disturbed  when  a  lower  carat  is 
used  in  a  subsequent  soldering  operation. 


DEEP  SADDLE 


;'>09 


Deep  Saddle. — Wliere  there  Jias  heeii  a  c-onsiderahlc  aniuunt  i)f 
resorption  and  there  is  a  great  (lei)th  between  the  occhiding  teeth 
and  the  ridge,  it  wonld  make  these  bridges  unneeessarily  and  unde- 
sirably heavy  to  l)uild  solid  bases  extending  from  the 
crowns  to  the  saddle.  This  will  appl.N-  where  there  is 
to  be  an  abutment  at  each  end  of  the  bridge,  and 
also  in  extension  saddles  which  are  anchored  only 
at  one  end,  as  in  the  lower  jaw  where  the  molar's 
are  missing.  The  bases  may  be  made  in  the  form  of  a  ring,  co\ering 
the  beveled  edge  and  extending  only  far  enough  underneath  to  form 
a  positive  seat  for  the  crown,  as  in  Fig.  562. 

After  the  crowns  have  been  ground  in  place,  they  are  fastened 
in  position  with  sticky  wax  and  plaster  is  flowed  over  the  occlusal 
surfaces  extending  over  the  buccal  and  lingual  sides  for  a  short 
distance  and  engaging  the  plaster  teeth  or  model  at  either  end,  as  in 


Fig.  5iy.i 


Fig.  563.  The  lower  edges  of  the  crowns  are  beveled,  as  Figs.  r>i]')  and 
556,  so  that  the  bases  may  extend  over  the  gingival  edges,  gripi)ing 
them  tightly,  thereby  aflording  a  firm  seat  and  minimizing  the 
possibility  of  a  fracture.  They  should  be  beveled  so  that  the  line 
of  the  bevel  on  the  buccal  and  lingual  sides  will  follow  the  natural 
curve  of  the  occlusal  surfaces  so  as  to  ])resent  a  symmetrical  ap])car- 
ance  which  would  not  !)(•  the  case  if  they  were  beveled  carelessly, 
one  being  shorter  than  the  other.  This  can  be  done  very  easily, 
as  the  occlusal  ends  of  the  crowns  resting  in  the  plaster,  expose  the 
entire  body  of  the  crown,  the  operator  can  plainly  see  what  he  is 
doing  and  nothing  is  left  to  guess  work. 

The  })ases  of  the  crowns  are  then  tinned  in  the  manner  already 
described  and  slio\ilil  be  made  sotliex  will  barely  touch  mesially  and 
distalK'  and  arc  cauglit  witli  very  little  stick\    wax   (Ui   the  buccal 


310    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

and  lingual  sides  (Fig.  564,  a  and  b) .  If  there  is  a  porcelain  crown  on 
the  mesial  abutment,  the  base  of  this  should  be  made  and  attached 
to  the  cap.  The  other  bases  are  then  built  on  in  wax,  being  waxed 
against  the  base  on  the  anterior  abutment,  but  between  each  of  the 
others,  a  thin  piece  of  oiled  paper  should  first  be  placed,  completing 
the  base  over  the  first  crown,  then  smoothing  the  distal  side,  plac- 
ing in  the  waxed  paper  and  then  making  the  wax  base  for  the 
second  crown.  When  this  has  been  completed,  the  distal  side  is 
smoothed  off  and  another  piece  of  the  waxed  paper  is  put  in  and 


Fig.  565 

the  thitd  base  completed.  These  bases  are  all  beveled  inward,  as 
shown  in  the  illustration,  Fig.  565,  the  reason  of  which  will  be  seen 
later. 

The  sprue  wire  is  now  attached  to  either  the  buccal  or  lingual 
sides,  as  in  Fig.  566,  and  each  of  the  bases  are  cast  separately  in 
coin  gold.  After  casting,  they  are  cleaned  in  hydrofluoric  acid. 
They  are  now  fitted  to  the  crowns  and  it  is  rarely  that  it  will  be 
found  necessary  to  do  any  trimming  in  order  that  the  crowns  may. 
be  properly  seated,  except  to  cut  out  any  little  bits  of  the  metal 
which  may  be  there  owing  to  small  bubbles  in  the  investment. 

The  buccal  and  lingual  sides  are  then  smoothed  by  beveling 
downward  and  inward,  as  already  stated.  The  occlusal  surfaces 
of  the  crowns  are  pressed  into  the  plaster  impression  and  are  tacked 
lightly  on  the  buccal  and  lingual  sides  with  sticky  wax.  The  cast 
ring  bases  are  then  placed  on  the  crowns  and  are  pressed  tightly 
in  place  and  waxed  together  with  sticky  wax,  after  which  they  are 
removed,  invested  and  united  with  21 -carat  solder.  These  united 
bases  are  then  placed  back  on  the  crowns  and  tacked  lightly 
with  wax,  the  whole  being  suspended  from  the  plaster  impression 
extending  over  the  occlusal  surfaces,  as  in  Fig.  563.  They  are  then 
placed  on  the  model,  as  in  Fig.  563,  and  the  bases  are  attached 
firmly  to  the  abutment  caps  at  either  end  or  where  there  is  an 
extension  saddle  mesially  to  the  base  of  the  crown  serving  as  an 
abutment  and  distally  to  the  saddle  on  which  the  last  ring  should 
rest,  as  in  Fig.  567. 


DEEr  SADDLE 


311 


The  crowns  are  tJieu  renioNed  and  the  saddle  is  in\ested  for 
soldering.  The  under  side  of  the  saddle  and  abutment  cap,  or  caps, 
are  filled  with  the  investment  and  the  remaining  investment  is 
placed  on  the  slab  and  smoothed  off,  lea\ing  it  about  one-half  an 


Fig.  566 


inch  in  depth.  The  saddle  is  then  settled  lightly  in  place  to  the 
depth  of  about  one-eighth  of  an  inch  and  some  of  the  investment 
brought  over  the  saddle  at  the  middle  part  and  under  and  over 
the  middle  ring,  but  not  coming  near  the  mesial  or  distal  ends 
which  are  to  be  united  to  the  abutments  or  the  saddle,  as  shown 
in  Fig.  o()S,  a  and  b.    The  inside  of  the  exposed   rings  and  the 


Fig.  .')68 


inside  of  the  base  on  the  abutment  caps  are  well  coated  with  anti- 
flux  and  the  investment  is  heated  up  and  soldered  with  2l-carat 
.solder,  enough  of  the  solder  being  used  to  unite  the  rings  firmly. 

The  .saddle  is  then  clean.sed  and  thoroughly  dried  and  all  the 
crowns  placed  in  their  proper  positions  ])reparatory  to  the  final 
step  in  the  making  of  the  bridge. 

The  si)acc  between  the  saddle  and  the  ring  l)ases  of  the  crowns 
is  now  filled  with  pink  paraffin  and  wax  both  on  the  buccal  and 
lingual  sides.  The  wax  is  then  carefully  carved  so  as  to  restore  the 
natural  contour  of  the  gum.  .\bout  one-eighth  of  an  inch  of  the 
edge  of  the  saddle  is  left  exposed  and  the  wax  carried  up  to  about 
midway  on  the  labial  and  lingual  sides  of  the  ring  ba.ses,  as  shown 
in  I''ig.  ^)V)').     It  is  then  f;irefnll\-  smoothed  arHJ  polished. 


312    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

Impressions  are  now  taken  of  the  carved  surfaces,  and  if  fusible 
metal  dies  and  counters  are  being  used,  the  impression  is  made 
deep  enough  to  serve  as  a  model,  but  if  lead  and  zinc  are  to  be  used, 
the  model  is  made  by  pouring  into  this  impression.  The  face  of 
the  model  should  extend  from  well  up  on  the  sides  of  the  crowns 
to  at  least  one-sixteenth  of  an  inch  below  the  lower  edge  of  the 
saddle.     (See  Fig.  601.) 

The  dies  and  counter  dies  are  made  and  plates  of  No,  28  or  No.  30- 
gauge  coin  gold  struck-up  and  carefully  fitted  and  adjusted  to  the 
saddle.  The  dies  should  be  perfectly  smooth  and,  if  necessary,  the 
surfaces  should  be  polished  before  swaging-up  the  plates.  One  of  the 
plates  is  carefully  adjusted  in  position  and  held  in  place  with  a  clamp 
over  the  edge  of  the  saddle,  and  the  piece  placed  in  the  invest- 
ment, open  side  down,  leaving  the  side  on  which  the  plate  is  to 
be  soldered  exposed,  as  in  Fig.  569,  The  investment  is  dried  out 
and  the  inside  of  the  ring  bases,  the  underside  of 
the  saddle  and  the  outside  of  the  plate,  to  within 
about  one-thirty-second  of  an  inch  of  its  edge 
all  around,  coated  heavily  with  whiting  or  other 
antiflux. 

It  is  then  well  fluxed  between  the  plate  and 

the  saddle  and  also  between  it  and  the  rings,  and 

Fig.  569  -j-j^g  parts  thoroughly  united  with  solder.    The 

solder  is  best  used  in  strips  and  should  be  20-carat. 

The  plate  is  first  united  to  the  ring  bases,  flushing  it  from  the 

upper  edge  of  the  plate  to  the  top  edge  of  the  ring,  as  in  point  a, 

Fig,  569, 

After  this  has  been  soldered,  the  plate  is  united  to  the  lower 
edge  of  the  saddle  at  point  b,  Fig.  569,  The  solder  is  used  in  a 
strip  and  is  fed  in  along  the  edge  of  the  saddle  between  the  two 
surfaces  until  it  has  thoroughly  drawn  through  at  all  points  through- 
out the  length  of  the  saddle,  uniting  the  saddle  and  plate  firmly. 
These  extension  saddles  should  not  be  chilled  quickly,  as  should 
this  be  done  there  is  a  liability  of  their  springing  and  becoming 
distorted.  They  should  be  allowed  to  cool  slowly  and  are  then 
removed  from  the  investment  and  cleansed. 

The  plate  for  the  opposite  side  is  next  clamped  in  position  and 
invested  in  the  same  way  as  for  the  plate  already  united.  It  is 
then  soldered  in  exactly  the  same  manner  as  the  first,  uniting  the 
plate  to  the  ring  and  afterward  to  the  saddle  and  after  cleansing 
and  drying  is  ready  for  finishing.     The  only  points  which  need 


EXTENSIOX  SADDLE  BRIDGES  313 

to  l)e  touched  with  the  stone  are  at  points  (t  a.  Fig.  070,  wliere  tlie 

plate  is  uniteil  to  the  ring  and  it  sliould  he  necessan'  only  to  smooth 

this  over  but  a  very  little  unless  au  excess  of  solder  has  lieen  used. 

The  edge  of  the   plate  and  saddle  at  })oints  b  h, 

Fig.  570,  should  be   smoothed   and  rounded.     It 

will  not  be  necessary  to  touch  the  face  of  the  plate 

with  the  wheels  if  the  dies  have  been  smooth,  as 

the  whiting  or  antiflux  which  has  been  placed  over 

the  face  should  prevent   any  solder  from  flowing 

down  over  it.    The  bridge  is  polished  as  already 

described,     following    the    carborundum     wheels 

with  fine  emery  and  cuttle-fish  disks  and  afterward  touching  lightly 

with  pumice  and  then  finishing  with  the  rouge.    The  bridge  is  now 

ready  for  the  attachment  of  the  crowns. 

The  object  in  making  a  saddle  bridge  in  this  manner,  instead 
of  casting  what  might  be  called  the  entire  shell,  and  then  uniting 
it  to  the  saddle,  is  that  the  rolled  coin  gold  plates  present  a  per- 
fectly dense  homogeneous  mass,  the  surface  of  which  can  be  easily 
polished,  and  which  takes  and  retains  a  very  high  finish,  while  the 
surface  of  a  casting  is  always  more  or  less  porous  and  will  not  take 
as  high  a  polish.  It  is  also  much  lighter  and  stronger  than  it  could 
possibly  be  made  by  casting. 

The  crowns  are  fitted  with  posts  which  extend  through  the  ()])en- 
ing  in  the  bases  into  the  body  of  the  saddle.  These  posts  may  be 
made  from  discarded  platinized  gold  split  pins,  the  lower  end  of 
which  is  sj)read  a  little,  as  shown  in  Fig.  570.  These  posts  are 
first  cemented  into  the  crowns.  The  hollow  body  of  the  saddle  is 
next  filled  with  cement,  and  the  crowns  put  in  ])lace  and  held  there 
under  pressure  until  the  cement  has  hardened  (Fig.  570),  after 
which  the  excess  cement  is  cleaned  away  and  the  bridge  is  ready 
for  the  mouth. 

A  saddle  bridge  made  in  this  way  presents  a  most  beautiful 
appearance  and  does  away  entirely  with  the  showing  of  the  gold. 
At  the  same  time  a  maximum  amount  of  strength  with  a  niininiiini 
amount  of  weight  has  been  obtained. 

EXTENSION   SADDLE    BRIDGES. 

'I'he  most  difficnit  piece  of  work  wliich  the  crown  ami  bridge 
specialist  may  be  calle<l  upon  to  do,  and  which  re(|nires  the  greatest 
skill  and  accuracy  in  its  acconii)lishnicnt ,  is  the  making  of  a  satis- 


314    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

factory  extension  saddle  bridge  for  the  lower  jaw,  restoring  the 
lost  molars  or  molars  and  bicuspids.  A  bridge  of  this  character, 
if  it  is  properly  made,  will  prove  as  satisfactory  as  any  piece  of 
bridge-work  which  can  be  placed  in  the  mouth.  On  the  contrary, 
if  it  is  not  made,  fitted  and  adjusted  as  it  should  be,  it  will  prove 
most  unsatisfactory^  and  will  ruin  the  abutment  teeth  more  quickly 
than  any  other  form  of  denture.  Extension  saddles  should'  not 
be  placed  in  the  mouth  excepting  where  the  teeth  have  been  out 
for  a  long  time  and  the  ridge  has  become  well  resorbed,  and  the 
tissues  are  well  hardened.  It  is  rarely  that  they  should  be  used 
unless  the  teeth  have  been  out  for  a  year  or  more. 

In  almost  every  case,  there  should  be  at  least  two  anchorages, 
either  two  bicuspids,  or  a  cuspid  and  bicuspid,  although  there  are 
cases  where  the  alveolar  ridge  is  very  pronounced  and  is  very  hard, 
especially  if  a  partial  plate  has  been  worn  for  a  number  of  years, 
where  a  single  anchorage  might  be  sufRcient. 

When  a  mouth  is  in  the  proper  condition  for  a  bridge  of  this 
character,  the  top  of  the  ridge  is  very  hard,  in  fact  there  is  but 
little  thickness  of  soft  tissue  over  the  bone  on  the  top  of  the  ridge, 
and  this  hard  ridge  will  not  be  much  more  than  one-sixteenth  of 
an  inch  broad,  the  tissues  thickening  gradually  on  either  side  as 
they  leave  it,  as  in  Fig.  571. 


Next  to  the  proper  preparation  of  the  abutment  teeth  or  roots, 
and  accuracy  in  making  and  fitting  the  abutment  crowns,  the 
success  of  a  bridge  of  this  kind  depends  upon  the  perfect  adaptation 
of  the  saddle  to  the  ridge. 

It  is  usually  best  to  first  make  the  abutment  caps  or  crowns. 
If  they  are  to  be  telescope  crowns,  then  these  crowns  should  be 
made  and  articulated,  and  also  connected  together,  making  sure' 
that  the  abutments  are  parallel.  If  they  are  to  be  porcelain,  or 
porcelain  faced  crowns,  the  entire  inner  caps  are  made  and  paral- 
leled, and  the  impression  taken  of  these.  A  model  is  prepared  and 
the  outer  half  caps  with  the  split  pins  are  made  and  united  together. 
These,  or  telescope  crowns,  if  they  are  to  serve  as  the  abutments, 
should  be  in  position  on  the  roots  when  the  impression  for  the 
saddle  is  taken. 


EXTENSION  SADDLE  BRlDdES 


-.ni-y 


Taking  the  Impression  and  Making  the  Dies  and  Counter  Dies. — 
The  next  step  is  to  secure  an  accurate  impression.  The  writer  has 
obtained  excellent  results  by  the  following  method: 

An  impression  of  the  ridge  is  first  taken  in  modeling  compound, 
using  a  sheet  of  the  compound  about  one-quarter  of  an  inch  thick 
and  not  softened  too  much.  This  is  passed  well  back  over  the 
abutment  teeth  and  ridge  and  pressed  down  at  the  back  and  on 
each  side  with  the  fingers  so  as  to  secure  as  good  an  adaptation 
as  is  possible.  It  is  then  removed  from  the  mouth  and  chilled. 
This  modeling  compound  impression  is  used  as  a  tray  for  taking 
the  plaster  impression.  The  plaster  is  mixed  fairly  stiff  so  that  it 
will  press  hard  on  the  soft  tissues.  This  composition  tray  is  filled 
with  plaster  in  the  usual  manner,  placed  in  position,  pressed  down 
firmly,  and  so  held  until  the  plaster  has  well  hardened. 

A  good  impression  ha^•ing  been  obtained,  the  model  is  then 
made  from  it.  It  should  be  of  good  depth,  at  least  one  inch  at  the 
shallowest  part,  so  that  there  will  be  no  chance  of  the  die  springing 
or  breaking  when  swagging  the  saddle  (Fig.  572). 


Fi<;.  .572 


The  model  having  been  prepare! ,  the  outline  for  the  saddle 
should  be  marked  upon  it.  The  saddk-  should  be  broad,  and 
should  be  carried  well  over  the  ridge  both  l)uccally  and  lingually, 
so  as  to  have  as  wide  a  bearing  on  the  ridge  as  it  is  possible  to 
get  for  the  wider  the  bearing  which  the  saddle  has,  the  greater 
will  be  its  usefulness  to  the  wearer. 

The  edges  of  the  saddle  should  be  turned  up  somewhat,  .so  that 
it  will  present  a  thick,  rounded  surface  to  the  soft  tissues,  and 
will  not  cjit  or  injure  thciii.  \  nuu-h  broader  saddle  can  be  worn 
with  comfort  by  having  the  edg<!S  well  nduidcd,  than  would  be  j)Os- 


316    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 


sible  if  the  edges  were  left  fairly  sharp.  These  edges,  when  the 
bridge  is  completed,  should  be  at  least  as  thick  as  a  No.  16-gauge 
wire.  In  order  to  turn  the  edge  of  the  saddle,  the  model  is  built 
up  with  wax  as  shown  in  Fig.  572,  before  die  and  counter  die  are 
made.  This  die  and  counter  die  may  be  made  of  zinc  and  lead 
or  of  fusible  metal  throughout.  The  waiter  prefers  the  latter 
because  of  the  absence  of  contraction  on  cooling,  and  also  on 
account  of  the  ease  with  which  it  is  manipulated. 

The  Saddle. — The  saddle  is  swaged  of  soft  platinum  of  No. 
32  or  No.  34  gauge.  Platinum  is  always  prefered  wherever  a 
saddle  is  used,  as  the  tissues  take  more  kindly  to  this 
metal,  and  it  will  keep  a  clean  polished  surface  even 
better  than  will  pure  gold.  Then,  too,  higher  grades 
of  solder  may  be  used  than  would  be  possible  with 
pure  gold.  The  saddle  should  be  large  enough  to 
allow  for  the  edge  being  turned  up  all  around  (Fig.  573).  The 
little  swaging  mallet  shown  in  Fig.  574  is  very  useful  in  working 
down  the  platinum  saddles  before  swaging  them  between  the  die 
and  counter.  It  has  a  rawhide  peen  and  will  not  mar  the  platinum. 
The  saddle  is  hammered  over  the  die  and  can  be  brought  down 
close  enough  for  swaging  easily  and  in  a  very  short  time.    During 


Fig  573 


Fig.  574 


the  swaging  it  should  be  frequently  annealed,  but  should  always 
be  cleansed  in  nitric  acid  after  swaging  before  trimming  or  heating 
it  up  again.  After  the  fmal  swaging,  it  is  again  cleansed  in  acid  and 
fitted  to  the  modeh 

The  platinum  being  very  soft  is  reinforced  to  strengthen  and  stiffen 
it  and  this  is  done  with  coin  gold.  The  underside  of  the  saddle 
is  painted  with  an  antiflux  or  whiting  as  is  the  top  of  the  ridge  back 
to  within  about  one-eighth  of  an  inch  of  the  distal  end  and  also 


EX  TEX  SI  ox  SADDLE   BRIDGES 


317 


at  the  front  where  it  turns  up  to  meet  the  aneh()raji;e  or  ahutnient 
at  that  i)oint  to  wliieh  it  will  be  attached  (Fig.  575).  This  is  to 
prevent  the  gold  from  flowing  over  these  places  and  the  underside 


Fig.  575 


^\ 


Fig.  576 


of  the  saddle.  The  coin  gold  is  then  flowed  o\er  the  exposed  }:>arts 
of  the  saddle  bringing  it  flush  with  the  turned-up  edges  of  the 
platinum  and  distributed  as  even  as  possible,  as  in  Fig.  576.  After- 
ward it  is  made  smooth  with  a  carborundum  wheel.  The  flowin<r 
of  the  coin  gold  over  the  platinum  will  have  distorted  it  somewhat, 
so  that  it  will  be  necessary  to  swage  it  again  and  after  this  has 
been  done,  it  is  again  cleansed  in  the  acid  and  is  ready  for  adjust- 
ment in  the  mouth. 

The  teeth  which  are  to  serve  as  abutments  have  already  been 
prepared,  and  the  inner  caps  made  and  placed  in  position.  The  next 
.step  is  that  upon  which  the  success  of  this  form  of  denture  entirely 
depends — the  accurate  adjustment  of  the  saddle  to  the  ridge. 

The  Adjusting  of  the  Saddle  to  the  Ridge. — The  front  end  of  the 
saddle,  which  is  to  ctmnect  with  the  abutment,  and  which  was  not 
covered  with  coin  gold  is  turned  back  a  little  so  that  it  will  clear 


A 


Fir;.  577 


Fig.  57S 


the  abutujcnt  when  it  is  in  jilace.  It  is  now  placed  in  the  nw»uth 
with  tin-  forefinger  of  each  hand  resting  on  either  side  of  the  sad<lle, 
pressing  it  in  place  and  is  rocked  frr)m  side  to  side.  It  will  be  found 
that  it  is  resting  on  the  top  of  the  ridge  fFig.  577j.     It  is  riding  on 


318    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

a  little  ridge  of  bone  not  over  one-sixteenth  of  an  inch  wide,  and  is 
not  bearing  anywhere  else.  Should  this  condition  not  be  remedied 
resorption  would  rapidly  take  place,  allowing  the  piece  to  sag, 
and  bringing  the  whole  strain  on  the  abutments,  with  the  result 
that  within  a  comparatively  short  time  the  roots  would  be  loosened 
and  lost. 

The  rocking  of  the  saddle  from  side  to  side  will  give  an  idea 
as  to  the  amount  of  correction  which  will  be  needed.  The  saddle 
is  removed  from  the  mouth  and  placed  on  the  die.  It  is  then 
raised  off  from  the  die  a  little  and  the  sides  pressed  inward  to  it, 
the  fingers  grasping  the  lower  edge  of  the  saddle  at  points  a  and  a, 
Fig.  578.  It  is  then  replaced  in  the  mouth  and  tested  again  by 
rocking  it.  Should  the  saddle  still  rock  a  little,  it  is  again  removed 
and  the  sides  pressed  still  further  together.  It  is  again  placed  in 
the  mouth  and  tested,  and  this  is  repeated  until  the  saddle  sets 
perfectly  solid  without  any  rocking  and  rests  comfortably  on  the 
ridge.  If  it  is  found  that  the  sides  have  been  brought  together  too 
much,  so  that  it  presses  too  hard  on  either  side  of  the  ridge,  it  is 
again  fitted  to  the  die  and  the  operation  repeated  until  the  saddle 
is  perfectly  comfortable  and  immovable  under  pressure. 

Securing  the  Relation  of  the  Saddle  to  the  Abutments. — The  front 
end  of  the  saddle  has  been  turned  back  so  that  it  will  clear  the 
abutments.  After  it  has  been  adjusted,  it  must  be  ascertained  that 
it  still  clears  the  abutment,  as  should  it  touch  it  in  the  least,  it  may 
be  pressing  against  the  abutment  much  more  heavily  than  would 
be  suspected  and  so  be  forcing  the  saddle  back  out  of  position. 


Fig.  579 


The  next  step  is  to  get  an  impression,  securing,  accurately  the 
relation  of  the  saddle  to  the  abutment  caps.  The  saddle  is  pressed 
firmly  into  position  on  the  ridge,  and  held  tightly  in  place  with 
as  much  pressure  as  can  be  brought  to  bear  on  it  with  the  thumb 
or  forefinger  of  the  left  hand,      A  saddle  on  the  left  side  of  the 


EXTENSION  SADDLE  BRIDGES 


319 


mouth,  is  held  down  witli  the  thumb,  the  fingers  pressing  the 
underside  of  the  mandible  (Fig.  579).  Should  the  saddle  be  on 
the  right  side  of  the  mouth,  it  is  held  in  place  with  the  forefinger 
of  the  left  hand  with  the  thumb  pressing  on  the  underside  of  the 
jaw  (Fig.  580). 

The  plaster  is  then  mixed  in  the  same  maimer  as  for  taking  an 
ordinary  impression,  but  more  of  the  potassium  sulphate,  or  what- 


FiG.  580 


ever  may  be  used  to  hasten  the  setting,  should  be  used,  as  the 
plaster  for  this  purpose  should  set  very  quickly.  The  plaster  is 
placed  in  the  mouth  with  the  spatula,  covering  the  abutments, 
and  the  end  of  the  thumb  or  forefinger  which  is  holding  the  saddle 
in  place  and  also  covering  the  surface  of  the  saddle  wherever  it  is 
exposed.  The  saddle  should  be  held  very  firmly  and  steadily 
until  the  plaster  has  thoroughly  hardened.  The  impression  is  then 
removed  from  the  mouth  together  with  the  saddle  and  abutment 
caps.  These  are  rei)laced  in  the  impression  and  attached  firml\'  in 
their  respective  position  with  sticky  wax.  The  inside  of  the  inner 
caps  are  now  given  a  thin  coating  of  pink  paraffin  and  wax  so  that 
they  can  rcadil.v  be  removed  from  the  model  after  casting. 

A  small  model  not  much  more  than  the  width  of  the  saddle  is 
then  made.  It  should  be  of  sufficient  depth  so  that  there  will 
be  no  liability  of  the  model  being  broken,  and  after  it  has  sufficiently 
lianh'ned  the  caps  and  saddle  are  removed  and  it  is  trinnned  and 
cleansed  of  the  wax  with  chloroform. 

The  al)Utment  cji|)s  and  saddle  are  then  replace<l  on  the  model 
and  the  anterior  j)art  of  the  saddle,  o\-er  which  no  coin  gold  has 
been  flowed,  is  pressed  over  against  the  caps  and  trimmed  so  that 
it  comes  just  af)out  to  the  lower  edge  of  the  outer  caj),  should  it 
lie  a  telescope  crown,  as  in  Fig.  oSl,  and  labiallx  and  lingnally  not 
rpiite  to  the  middle  <»f  the  cap  a>  (t  ii,  Fig.  5X2.  Should  the  attach- 
Micnts  be  caps  with  tiibe>  and  ^plit  pins,  where  facings,  or  porcelain 


320    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

crowns  are  used  the  saddle  should  be  fitted  to  the  lower  edge  of 
the  half-band  and  extend  part  way  labially  along  the  floor  to  a  a, 
Fig.  583. 


Fig.  581 


This  end  of  the  saddle  is  then  tacked  to  the  abutments  with 
sticky  wax  and  a  piece  of  iron  wire  is  bent  over  the  occlusal  surface 
or  the  floor  of  the  caps  and  carried  along  the  saddle  and  waxed 
firmly  in  position  with  hard,  sticky  wax  (Figs.  584  and  585).    This 


Fig.  584 


Fig.  585 


is  to  prevent  the  possibility  of  distortion  when  the  inner  caps 
are  removed  and  the  saddle  is  being  invested.  The  inner  caps  are 
now  removed  and  the  saddle  with  the  outer  caps  attached  are 
invested.  The  outer  caps  are  filled  with  investment  which  should 
cover  the  lower  edges  of  the  saddle;  only  a  sufficient  amount  being 
used  to  hold  the  parts  in  position  during  the  soldering  (Fig.  586). 


Fig.  586 


It  is  then  warmed  up,  the  bulk  of  the  wax  removed  and  the 
whole  heated  until  the  remainder  of  the  wax  has  burned  away, 


EX  TEN  SI  0\  SADDLE  BRIDGES 


m 


or  the  wax  can  be  melted  out  with  a  stream  of  boihng  water,  after 
which  it  is  cooled  slightly  and  fluxed  well  between  the  saddle  and 
the  caps.  The  whole  is  then  heated  up  and  the  caps  and  saddle 
are  united  with  21-carat  solder,  using  plenty  of  the  sokler  and 
flowing  it  heavily  over  the  platinum  of  the  saddle  which  has  not 
been  covered  with  the  coin  gold.  After  it  has  cooled,  it  is  remo^•ed 
from  the  investment  and  cleansed  in  acid,  and  after  it  has  d'ried, 
it  is  replaced  on  the  model,  with  the  inner  caps  in  place.  It  will 
probably  be  found  that  when  the  caps  are  pressed  in  position  on 
the  model,  that  the  saddle  will  be  raised  somewhat  at  the  farther 
end  (Fig.  587).    This  is  due  to  the  solder,  of  which  a  considerable 


Flu.  5S7 


amount  has  been  used,  contracting  on  cooling  and  thus  drawing 
up  the  end. 

In  order  to  make  up  for  this  contraction,  it  will  be  necessary  to 
grasp  the  abutment  caps,  and  raising  the  caps  and  saddle  a  little 
off  the  model,  press  the  distal  end  of  the  saddle  down,  thus  spring- 
ing it  back  a  little  at  a  time  until  it  assumes  its  proper  position 
on  the  model.    It  is  now  ready  for  taking  the  articulation. 

Taking  the  Articulation. — The  saddle,  with  the  inner  caps  in 
position,  is  now  jjlaced  in  the  mouth  and  carefully  examined  to 
see  that  the  parts  are  in  proper  relation.  \Vhen  the  caps  are  pressed 
in  place  the  saddle  should  remain  firmly  seated  on  the  ridge,  and 
the  api)liance  should  be  jxTfectlx'  comfortable  to  the  })atii'nt.  In 
securing  the  articulation  for  this  j)iece,  wax  or  modeling  coin- 
poimd  may  be  used,  as  the  a|)pliance  will  probably  come  away 
with  the  imjjression  and  there  will  b<!  little  danger  of  distortion 
of  the  articulation  as  there  might  be  if  it  had  to  be  pressed  back 
o\'er  a  uhmIcI. 

The  writer,  ho\ve\cr,  prclVrs  plaster  in  all  cases,  as  in  using 
plaster  there  is  a  certainty  that  a  perrect  iirti(  iiliition  will  have  been 
secured.  This  is  taken  in  the  sanif  manner  as  in  oilier  cases,  the 
21 


322    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

plaster  covering  the  saddle  well  back,  as  well  as  the  abutment 
caps,  and  taking  in  two  or  three  of  the  teeth  anterior  to  it.  Some 
plaster  is  placed  over  the  occluding  teeth  and  the  patient  is 
instructed  to  close  the  jaws,  the  other  teeth  not  included  in  the 
impression  being  examined  to  see  that  the  occlusion  is  correct. 

^Yhen  the  plaster  has  hardened,  it  is  removed  from  the  mouth, 
and  the  saddle,  with  the  inner  caps  in  place,  are  replaced  in  the 
impression.  The  inside  of  the  inner  caps  are  then  given  a  coating 
of  pink  wax  and  the  saddle  and  outer  caps  are  waxed  firmly 
in  the  impression,  any  under-cuts  which  may  appear  in  the  saddle 
being  filled  out  with  pink  wax  so  that  the  saddle  will  draw  readily 
after  the  model  has  been  made.  The  model  is  prepared  and 
articulated  in  the  same  manner  as  for  an  ordinary  bridge. 

After  the  model  has  hardened,  it  is  separated  from  the  impres- 
sion, the  saddle  is  removed,  cleansed  of  wax  and  is  ready  for  the 
adjustment  of  the  crowns,  or  it  may  be  finished  in  any  way  that 
may  seem  desirable. 

There  are  many  methods  of  finishing  these  bridges.  The  teeth 
may  be  attached  with  vulcanite,  crowns  of  various  types  may  be 
used  or  tube  teeth,  diatoric  teeth,  or  interchangeable  teeth — now 
and  again  prove  very  satisfactory. 

Vulcanite  Attachment. — Where  a  vulcanite  attachment  is  used, 
the  attachment  of  the  saddle  to  the  abutment  caps  must  be  rein- 
forced. If  telescope  crowns  have  been  used,  round  or  half  round 
platinized  gold  clasp  wire  may  be  attached  near  the  occlusal  end 
of  the  outer  caps  and  passed  down  to  the  saddle  with  three  or  four 
loops  along  its  length,  to  firmly  secure  the  vulcanite  to  the  saddle, 
as  in  Fig.  588. 


Fig.  588 

AYhere  caps,  with  tubes  and  split  pins,  are  used  as  abutments, 
a  loop  of  the  half-round  clasp  wire  may  be  run  across  the  caps 
and  back  and  over  the  saddle,  as  in  the  other  case  (Fig.  589).  In 
either  case,  in  using  half  round  wire,  the  rounded  side  of  the  wire 
should  be  next  to  the  saddle  and  caps. 


EXTENSION  SADDLE  BRIDGES 


6Z6 


For  the  attachment  of  the  vulcanite  to  the  sides  of  the  saddle, 
the  coin  gold  covering  is  well  stippled.  This  will  make  a  very  strong 
attachment  and  one  which  will  hold  as  well  as  any  that  could  be 
devised.  In  stippling,  a  very  sharp-pointed  graver  should  be 
used,  and  it  should  be  well  and  deeply  stippled  in  both  directions. 


Fig.  589 

This  will  make  a  very  strong  union,  so  that  the  vulcanite  cannot 
be  torn  away.  This  will  apply  where  the  ordinary  vulcanite  pin 
teeth  or  the  diatoric  teeth  are  used. 

Where  Facings  are  Used  with  a  Gold  Occlusal  Surface. — In  mak- 
ing the  bridge  where  facings  are  used  with  a  gold  occlusal  surface, 
it  is  better  that  the  facings  should  not  be  ground  to  fit  the  saddle 
exactly,  but  should  stand  away  from  it  for  from  one-thirty- 
second  to  one-sixteenth  of  an  inch,  as  in  Fig.  590.    The  object  of 


Vui.  .390 


Fk;.  i>\n 


tiiis  will  be  seen  later.  It  is  inijjossiblc  to  grind  the  facings  so  tliat 
they  will  fit  tlic  saddle  so  perfectly  as  to  prcxcnt  foodst nil's  or 
saliva  from  working  in  bciicatli  tliciii.  It  makes  no  dill'crence 
how  nnicli  time  is  spent  d(»ing  it,  and  even  tliongli  (lie  joints  are 
njadc  \cry  close,  tlicy  will  not  be  so  after  soldering.  The  tips  of 
the  facings  should  be  liigli  cnon;;li  to  touch  tlic  lingual  surfaces  of 
tlic  buccal  cusjjs  of  tlic  occluding'  tcctli,  ;is  in   V\ii.  .')!)()  a. 

After  tli<'  facings  ha\('  been  ground,  tlicy  ;irc  licid  in  |)lacc  with 


324    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

wax  on  the  lingual  side,  and  a  wall  of  plaster  built  up  on  the  buccal 
side  nearly  to  the  occlusal  ends  of  the  facings,  so  as  to  retain  them 
in  position  after  the  wax  has  been  removed  (Fig.  591).  The  facings 
are  then  removed  and  the  occlusal  ends  ground  off  at  an  angle  of 
about  forty-five  degrees  with  the  backs  or  lingual  side,  as  in  Fig. 
590  a,  leaving  them  of  sufficient  length  so  that  they  will  clear  the 
occluding  teeth  by  about  from  one  sixty-fourth  to  one  thirty-second 
of  an  inch.  This  angle  should  be  the  same  on  all  the  facings,  and 
the  line  on  which  they  are  ground  should  be  continuous,  one  follow^- 
ing  the  other  as  though  they  had  all  been  attached  together  and 


Fig.  592 

then  ground  (Fig  592).  It  will  spoil  the  appearance  of  the  piece 
if  they  are  ground  unevenly,  so  that  the  tip  of  one  is  higher  than 
the  other,  one  standing  up  and  the  other  down  and  it  will  look 
as  though  the  piece  had  been  thrown  together  haphazard,  without 
care  for  artistic  effect  (Fig.  593). 

The  facings  are  then  backed  with  thin  platinum,  the  backings 
touching  or  overlapping  each  other  slightly  and  extending  from 
the  beginning  of  the  bevel  at  the  occlusal  end  to  the  saddle,  which 
they  should  touch  closely  all  along,  being  carried  straight  down  on 
a  line  with  the  backs  of  the  facings  (Fig.  592).  The  pins  are  then 
flattened  and  bent  upward  or  downward,  pressing  on  the  back- 
ings to  hold  them  tightly  against  the  facings. 


Fig.  593 


Fig  594 


The  facings  are  then  waxed  firmly  to  the  saddle  with  hard  sticky 
wax,  the  wax  being  carried  high  enough  to  support  and  hold  the 
cusps  but  not  flush  with  the  lingual  side  of  the  cusps  (Fig.  594). 


EXTEXSIO.X  SADDLE  BRIDGES  325 

Cusps. — Solid  gold  cusps  are  used,  and  they  are  selected  and 
made  in  the  same  manner  as  are  the  cusps  for  a  shell  or  telescope 
crown.  The  buccal  side  of  the  cusps  are  ground,  or  filed  to  a  bevel 
to  fit  the  bevel  of  the  facings  (Fig.  594).  As  each  one  is  fitted,  it 
is  waxed  lightly  in  place  until  they  are  all  in  position. 

They  are  then  ground  or  filed  away  on  the  lingual  side  so  as  to 
even  them  and  not  have  one  cusp  broader  or  standing  further 
lingually  than  the  other.  They  should  also  be  filed  on  a  slight 
angle  so  as  to  follow  the  line  of  the  lingual  side  as  it  will  be  when 
it  is  completed.  This  will  gi\e  a  broad  point  of  contact  for  the 
lingual  plate  when  in  position  and  in  finishing  there  will  be  no 
danger  of  grinding  through  into  the  hollow  space  on  the  inside  of 
the  bridge  (Fig.  595).  If  the  cusps  were  not  beveled  in  this  manner, 
the  edge  of  the  cusp  coming  down  as  it  does  to  a  sharp  angle,  it 
can  be  seen  in  the  illustration  (Fig.  59(3)  that  the  point  of  contact 


Fig.  .59.5  Fio.  .590  Fk;.  597 

would  be  but  slight  and  if  it  were  ground  off  a  very  little  in  finish- 
ing it  would  break  through  into  this  hollow  space  beneath.  If  the 
cusps  were  overbeveled,  or  cut  under,  the  efi'ect  would  be  practically 
the  same  (Fig.  597). 

After  they  have  been  ground  and  fitted,  they  are  attached  firmly 
with  hard,  sticky  wax,  but  the  wax  should  not  extend  to  the  lingual 
edge  of  the  cusps.  After  they  have  been  attached,  the  small  end 
of  the  wax  spatula  is  heated  a  little  and  pas.sed  under  the  cusp  and 
raised  slightly  CFig.  594  a),  lifting  the  cusp  on  the  lingual  side  so 
that  on  the  buccal  side  the  beveled  edge  of  the  cusp  and  facing  will 
toucli  lightly  at  the  tip,  but  there  will  not  be  actual  contact  at  the 
lower  or  iiuier  side  of  the  bevel.  The  buccal  and  lingual  sides  of 
the  bridge  are  now  ready  to  be  finished. 

Waxing  and  Carving  for  the  Plates. — The  buccal  and  lingual  sides 
arc  covered  w  itii  wax,  making  the  lingual  side  more  than  flush  with 
the  lingual  side  of  the  cusps  so  as  to  have  plenty  of  stock  for  carving.^ 
The  pink  paraffin  and  wax  is  preferable,  as  it  is  fairly  hard,  is  not 
sticky,  and  curves  nicely.  Both  sides  are  then  carved  to  represent 
tlie  natural  gums.  On  tlu'  buccal  side  it  should  be  carried  a  little 
uboN'e  the   lower  edge  of  tlic   fiicitigs  and    well    up   between   tlieni. 


326    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

as  in  Fig.  59S.  On  the  lingual  side,  the  car\ing  is  made  continuous 
with  the  lingual  angle  of  the  cusp,  as  in  Fig.  599,  and  the  carving 
should  correspond  in  depth  and  breadth  to  the  facings  on  the  buccal 
side. 


Fig.  598 


Fig.  599 


The  carving  should  be  carefully  done  and  the  surface  of  the  wax 
made  perfectly  smooth,  in  order  to  insure  the  obtaining  of  a  clean 
die  so  that  when  the  plates  are  struck  up  they  will  be  perfectly 
smooth  and  when  the  bridge  is  completed,  they  will  require  no 
finishing  other  than  with  the  pumice  and  rouge. 

An  impression  is  then  taken  of  each  side  separately,  the  plaster 
being  carried  from  below  the  saddle  to  above  the  gum  line  and 
over  the  heel  on  the  buccal  side,  as  in  Fig.  600.     On  the  lingual 


Fig.  600 


Fig.  601 


side,  the  plaster  is  carried  above  the  cusps  and  below  the  edge  of 
the  saddle  (Fig.  601)  and  far  enough  over  the  heel  to  meet  or  overlap 
the  impression  from  the  buccal  side. 

If  zinc  and  lead  dies  and  counter  dies  are  to  be  used,  a  model 
should  be  poured  into  the  plaster  impression,  as  owing  to  the 
shrinkage  of  the  zinc  it  is  desirable  that  the  face  of  the  die  should 
present  the  face  of  the  carved  facings  and  not  the  reverse  side. 
If,  however,  fusible  metal  is  used  for  the  die  and  counter,  the 
impression  may  be  made  deep  enough  to  serve  as  a  model,  as  with 
this  metal  there  is  practically  no  shrinkage  and  it  will  make  no 
difference  whether  the  face  of  the  die  presents  the  cameo  or  intaglio 


EXTEXSfOX  SADDLE   BR  I  DUES  Wll 

.(Fig.  ()01).    These  models  should  W  at  least  one  iiieli  in  drpth  so 
that  there  will  be  no  saii;<;in^'  or  sprinoini.-  of  the  die  in  swaj^niig-. 

Where  fusible  metal  is  used,  the  sides  of  the  model  slioiild  be 
made  nearly  parallel  so  tliat  the  dies  will  be  of  that  shape.     The 


Fig.  602 

mould  may  be  made  of  .saud,  or  preferably  of  Dr.  (Jritman'.s  calear,' 
and  the  fusible  metal  poured  in  this.  It  will  only  be  neeessarv 
to  get  one  die  for  eaeh  side  from  a  ealear  mould,  as  all  the  other 
dies  and  counter  dies  which  are  needed  can  be  .secured  from  the 
original  casting. 

'i'he  metal  should  be  poured  in  the  mould  when  it  is  not  in  a 
very  liquid  state,  but  it  should  be  hot  enough  to  allow  it  to  pour 
fairly  freely.  This  die  i>  then  chilled  and  wrapped  in  paper  and  a 
gum  band  [>laced  around  it,  as  in  Fij,'.  (■)()2.  The  sides  of  the  die 
being  parallel  makes  it  of  a  good  shape  for  pourinj;  the  counter 
die.     The  die  is  then  dusted  with   talcum    powder  and   the  coimter 


'  Marl>l<'  (iiiHt,    rn(jiMl«'ii<'l    with    glycerin    riii<l  w.itcr,    ii   clcjirily,    :uiii    t;ik<s   Hit 
|j|;w<'  fif  tii'ililinK  .h;iii(|. 


328     PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

die  poured.  In  pouring  the  counter  die,  the  metal  should  be  as 
cold  as  it  is  possible  to  pour  it.  It  is  poured  into  the  paper  on  the 
die  until  it  is  about  the  same  depth  as  the  die  itself. 

After  it  has  become  chilled,  it  is  readily  separated  and  another 
counter  poured  from  each  of  these.  By  wrapping  in  paper  and 
dusting  with  talcum  powder,  in  the  same  manner  as  in  the  first 
operation,  any  number  of  dies  and  counter  dies  can  be  secured 
and  everyone  will  be  an  exact  duplicate  of  those  just  made. 

If  the  die  is  chilled  and  the  counter  die  poured  as  cold  as  it  can 
be  made  to  flow,  they  will  not  stick,"  but  will  readily  separate.  As 
a  rule,  two  dies  and  counter  dies  will  be  sufficient  for  swaging  the 
plate,  especially  the  buccal  which  is  thinner  than  the  lingual  plate 
but  for  the  lingual  side  it  is  sometimes  well  to  use  three  as  a  sharper 
outline  will  be  obtained  in  the  plate  than  if  only  two  had  been  used. 

The  dies  and  counter  dies  made,  the  buccal  plate  is  struck  up 
from  No.  30-gauge  coin  gold,  festooned  carefully  to  fit  around  the 
facings  accurately  and  carried  over  the  heel  of  the  saddle  to  about 
two-thirds  the  width  of  the  cusp  from  the  buccal  side.  The  lin- 
gual plate  is  struck  from  No.  28-gauge  coin  gold  and  carefully 
fitted,  the  part  going  over  the  heel  being  brought  in  contact  with 
that  from  the  buccal  side.  The  plates  should  be  cleansed  in  nitric 
acid  after  each  swaging  and  before  they  are  trimmed  or  annealed, 
otherwise  one  heating  after  swaging,  would  entirely  destroy  them. 


Fig.  60.3 


After  the  final  swaging,  and  when  the  plates  have  been  thoroughly 
cleansed  in  acid,  the  pink  wax  js  removed  from  .around  the  facings 
and  the  saddle  on  the  buccal  side.  The  buccal  plate  is  placed  in 
position  and  held  with  small  iron  clamps,  as  in  Fig.  603,  two  or 
three  clamps  being  sufficient  for  the  purpose.  The  saddle  is  then 
held  over  a  small  alcohol  flame  for  a  moment,  or  a  hot  instrument 
is  held  beneath  it,  to  loosen  the  wax  from  the  plate,  and  the  teeth, 
with  the  body  of  the  wax,  are  removed  and  laid  carefully  aside 
(Figs.  604  and  605). 


EXTENSIOX  SADDLE  BR  I  DUES  329 

Investing  the  Saddle. — The  inner  caps  are  removed  ami  the  saddle 
is  invested,  lingual  side  down,  only  enougli  of  the  investment 
being  used  to  keep  it  from  springing  (Fig.  60G).  The  inside  of  the 
caps  are  filled  with  investment,  care  being  used  not  to  allow  the 
investment  material  to  come  o\er  the  part  which  is  to  be  soldered. 


Fig.  604  Fic  605  Fi<;.  60() 

The  investment  should  then  be  thoroughly  dried  out,  the  piece 
well  fluxed  between  the  plate  and  the  saddle  and  some  pieces  of 
18-carat  solder  dropped  in  where  the  saddle  and  the  plate  are  to 
be  united  (Fig.  600,  a).  The  investment  is  then  well  heated  up  and 
when  it  has  reached  a  red  heat,  the  blow-pipe  flame  is  thrown 
on  the  underside  of  the  saddle  next  to  the  investment  and  the 
solder  drawn  through  from  the  inside  all  around. 

As  the  solder  begins  melting  at  one  point,  tiic  flame  of  the  blow- 
pipe is  moved  along  slowly  from  end  to  end  until  the  solder  shows 
all  along  the  outer  edge,  giving  a  perfect  union  between  the  [)late 
and  the  saddle.  Twenty-carat  coin  solder  may  be  used  for  this 
purpose,  but  as  the  coin  solder  has  a  much  higher  fusing  point  than 
the  18-carat,  a  great  deal  more  care  is  rc(|uircd  in  using,  otherwise 
the  buccal  plate  may  be  burned.  In  using  the  2()-carat  solder,  it 
is  fed  along  and  drawn  in  from  the  outer  edge,  using  the  solder 
in  a  strip.  However,  as  the  solder  will  not  show  at  this  place, 
it  is  safest  to  use  the  18-carat. 

After  the  investment  has  been  allowed  to  cool  the  saddle  is 
removed,  cleansed  in  acid  and  dried.  The  saddle  is  then  warmed 
slightlv  and  the  body  of  the  bridge  (Fig.  (j()4)  is  pressed  back  into 
place  until  the  fitting  of  the  lingual  plate  shows  that  it  is  in  its 
correct  [)osition.    The  bridge  is  now  ready  for  the  filial  soldering. 

Soldering  the  Body  of  the  Bridge  and  the  Lingual  Plate.  In  all  sol- 
dering operations,  cleanline.ss  is  ab.solutely  essential,  and  there  is 
no  greater  enemy  to  the  free  flowing  of  solder  than  is  plaster-of- 
I'aris.  (Cleanliness  is  especially  needful  in  soldering  a  bridge  of  this 
character,  as  such  a  high  degree  of  heat  is  required  to  make  the 
solder  flow  in  places  whirh  are  deep  down  in  the  body  of  the  bridge, 


330    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 


that,  unless  perfect  cleanliness  is  obtained,  there  is  a  great  liability 
of  burning  the  exposed  parts.  All  of  the  parts  which  are  to  be 
soldered  should  be  covered  with  wax  before  investing.  The  invest- 
ment having  been  mixed  it  is  placed  on  the  slab  to  the  depth  of 
about  one-half  of  an  inch.  The  bridge  is  laid  buccal  side  down  on 
this  and  worked  into  it  for  perhaps  one-eighth  of  an  inch  by  using  a 
slight  pressure  on  the  lingual  side,  agitating  it  slightly,  and  keeping 
the  edges  of  the  cusp  and  the  lower  edge  of  the  saddle  on  a  level. 

With  a  small  instrument  (the  curved  end  of  the  small  wax  spatula 
is  suitable)  the  investment  is  worked  up  so  as  to  cover  a  little  more 
than  one-half  of  the  cusps  and  over  the  labial  side  of  the  saddle  so 
as  to  cover  about  one-half  of  it,  leaving  the  lingual  half  of  the 
saddle  and  the  lingual  third  of  the  cusps  exposed,  as  shown  in 
Fig.  607,  a  a. 


Fig.  607 


Fig.  608 


Fig.  609 


Before  the  investment  has  thoroughly  hardened,  it  is  trimmed 
to  the  proper  size  and  should  be  kept  as  small  as  possible,  and  still 
give  support  to  the  bridge.  All  of  the  trimming  should  be  done 
at  this  time,  before  removing  any  of  the  wax.  All  the  parts  which 
are  to  be  covered  with  solder  should  be  cleansed,  the  plaster  scraped 
off,  and  the  nearby  parts  rubbed  off  with  a  damp  cloth,. or  washed 
so  that  no  plaster  will  remain.  After  the  investment  has  hardened, 
it  is  warmed  a  little,  to  slightly  soften  the  wax  in  contact  with  the 
different  parts,  and  the  bulk  of  the  wax  is  lifted  out,  and  the  remain- 
der can  be  washed  out  with  boiling  water. 

It  should  then  be  dried  out  thoroughly  with  a  gentle  heat  and  a 
little  powdered  calcined  borax  sprinkled  inside  the  body  of  the 
bridge.  The  piece  is  then  heated  up  slowly  until  it  is  of  a  bright 
red  heat  and  it  is  ready  to  solder. 

Twenty-carat  solder  is  first  used  at  the  mesial  end  to  unite  the 
saddle  and  cusps  firmly  to  the  abutments  and  then  at  the  distal  end, 
should  there  be  an  anchorage  at  that  end,  or  should  the  cusp  be 
attached  to  the  end  of  the  saddle.  The  solder  is  then  flowed  over 
the  backings  of  the  teeth  and  over  the  saddle  and  up  to,  and 


EXTENSION  SADDLE  BIN  DOES  331 

between  the  cusps  so  that  all  the  exposed  parts  will  show  nothing 
but  20-carat  solder.  The  backings  of  the  facings  should  be  covered 
to  the  depth  of  perhaps  a  thirty-second  of  an  inch  or  sufficient  to 
cover  the  pins  of  the  facings  and  coming  up  on  the  saddle  and  the 
under  side  of  the  cusps,  as  shown  in  the  drawing  (P'ig.  GOS).  It  is 
not  necessary,  nor  is  it  desirable,  that  this  space  be  entirely  filled, 
as  that  would  make  the  bridge  entirely  too  heavy,  but  only  enough 
solder  is  used  to  give  the  necessary  strength  to  the  piece.  After 
this  has  been  finished,  the  soldering  of  the  lingual  plate  may  be 
undertaken.  The  under  surface  of  the  plate  at  the  upper  and  lower 
edges  is  well  fluxed,  using  the  liquid  flux  and  applying  a  little  at 
a  time  and  passing  it  through  the  flame  to  dry  it  off.  The  lower 
edge  of  the  saddle  and  also  the  lingual  sides  of  the  cusps  at  point 
a  and  a,  in  Fig.  608,  are  then  fluxed  and  a  little  IS-carat  solder  is 
flowed  over  these  points  throughout  the  length  of  the  bridge.  Sol- 
fler  is  best  used  in  a  strip  in  applying  it  to  these  points. 

The  piece  is  then  well  heated  up  and  the  lingual  plate  placed  care- 
full\-  in  i)()sition  (Fig.  (iOQ).  The  whole  bridge  is  brought  to  a  bright 
red  heat,  a  brush  Hame  being  used  until  the  solder  begins  to  melt, 
when  a  i)()inted  flame  should  be  used,  passing  it  along  the  upper 
side,  throwing  the  Hame  on  the  cusps  (Fig.  ()()9,  a),  and  moving  from 
one  end  of  the  bridge  to  the  other  until  the  solder  has  drawn  through 
at  every  point  and  the  jjlate  united  firmly  to  the  cusps.  If  there 
are  anv  points  where  the  plate  has  not  quite  dropped  into  position, 
a  pair  of  pliers  may  be  used,  one  beak  grasping  the  plate  where  it 
is  not  in  exact  contact,  the  other  beak  being  on  the  underside  of 
the  investment,  as  in  Fig.  (ilO,  a,  and  as  the  solder  flows,  the  i)late 
can  be  pressed  in  contact  with  the  cusps,  as  it  will  bend  very  easily 
under  heat. 

The  occlusal  side  of  the  j)late  being  proi)erly  attached,  the  oj)era- 
tor's  attention  is  next  turned  to  the  lower  side.  The  ])iece  is 
reversed  so  as  to  bring  the  lower  edge  of  the  saddle  toward  the 
operator,  and  the  Hame  is  thrown  on  the  under  part  of  the  saddle 
(Fig.  009,  b),  which  is  heated  until  the  solder  draws  freely  from  the 
inside  and  has  flowed  along  the  whole  length  of  the  saddle.  If  it 
stands  away  at  any  point,  it  should  be  brougjjt  together  with  tiie 
pliers  while  the  solder  is  molten,  until  it  is  in  perfect  contact  all 
around  fFig.  010,  h).  Over  the  heel  of  the  saddle,  where  the  buccal 
and  lingual  plates  come  in  contact,  a  little  solder  should  be  flowed 
until  the  two  plates  are  perfectly  united. 

Twenty-carat  solder  inay  be  used  f(»r  soldering  on  (lie  lingnal  plate 


332    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

by  first  fluxing  the  cusps  and  the  lower  edge  of  the  saddle  and 
then  placing  the  lingual  plate  in  position.  The  solder  is  used  in 
a  strip  and  a  small  amount  placed  at  a  point  of  contact  of  the  plate 
with  the  cusps,  tacking  it  a  little  at  first,  and  then  feeding  the  solder 


Fig.  610 


in  and  moving  it  along  slowly  from  one  end  of  the  bridge  to  the 
other.  The  lower  side  of  the  plate  is  now  attached  to  the  saddle 
in  the  same  manner,  feeding  in  the  solder  in  a  strip,  and  gradually 
drawing  it  through  from  one  end  to  the  other,  after  which  the  ends 
of  the  buccal  and  lingual  plates,  which  come  together  over  the  heel 
of  the  saddle,  are  soldered. 

The  20-carat  solder  is  of  a  so  much  higher  fusing  point  than  the 
eighteen  that  it  is  safer  to  use  the  18-carat  unless  the  operator 
is  an  expert  in  the  use  of  the  blow-pipe.  If,  however,  the  plate 
has  been  carefully  fitted,  the  line  of  solder  at  the  point  of  union 
of  the  cusp  with  the  plate  is  so  fine  that  the  difference  in  the  color 
will  not  be  noticeable.  The  greatest  care  must  be  used  in  solder- 
ing on  this  plate  and  the  pointed  flame  should  not  touch  it  as  the 
piece  is  necessarily  brought  to  such  a  very  high  heat  that  the 
lingual  plate  can  be  burned  in  an  instant,  thus  destroying  it,  and 
necessitating  making  a  new  one. 

After  the  bridge  has  cooled  it  is  removed  from  the  investment, 
boiled  in  dilute  sulphuric  acid  and  washed  in  a  solution  of  bicar- 
bonate of  soda  and  then  rinsed  in  clear  water.  It  is  next  dried  as 
well  as  possible  and  then  dipped  in  alcohol,  or  alcohol  poured  over 
it,  and  then  again  dried  thoroughly,  so  that  before  any  finishing 
is  undertaken,  there  will  be  no  moisture  in  any  part,  as  should 
there  be  any  moisture  present,  the  dust  of  the  grinding  will  work 
in  the  crevices  and  the  spaces  between  the  plate  and  facings,  leav- 


EXTEXSIOX  SADDLE  BRIDGES  ooo 

inu"  (lark  lines  which  will  present  a  very  disagreeable  appearance 
This  applies  to  the  finishing  of  all  bridges  or  crowns. 

The  bridge  is  then  finished,  first  nsing  fine  carbornndnm  wheels 
and  grinding  away  any  edges  of  the  cusps,  which  may  overhang 
the  facings,  luitil  tlie>-  are  perfectly  flush  with  the  facing. 

In  grinding  the  cusps  the  grinding  should  always  be  done  from 
the  gold  to  the  porcelain,  thus  burnishing  the  gold  over  the  facing 
and  making  perfect  joints.  By  so  doing  there  will  be  no  danger  of 
fracturing  the  thin  edge  of  the  facing.  On  the  contrary,  if  the  grind- 
ing is  from  the  porcelain  to  the  gold,  the  fine  edge  of  porcelain  at 
that  point  will  be  shivered,  making  it  rough,  and  impairing  the 
beauty  of  the  work. 

On  the  other  side,  the  lingual  plate  is  ground  flush  with  the 
cusps  and  the  lower  edge  of  the  saddle  on  both  Ijuccal  and  lingual 
sides  are  smoothed  and  rounded.  It  should  not  be  necessary  to 
touch  either  the  lingual  or  buccal  plates  with  the  stone,  if  care  has 
been  used  in  obtaining  smooth  dies,  and  the  plates  have  not  been 
marred  in  swaging.  The  heel  of  the  plate  is  finished  with  carborun- 
dum stones  and  afterward  all  of  the  parts  which  have  been  ground 
are  smoothed  oft*  with  sandpaper,  or  emery  disks,  and  then  cuttle- 
fish, so  that  there  will  be  very  little  finishing  to  do  on  the  lathe. 

The  piece  is  now  i)laced  on  the  model  and  articulated  and  the 
cusj)s  are  carved  as  desired. 

Filling  Beneath  the  Buccal  Plate  with  Cement. — The  next  step, 
before  the  final  polishing  of  the  piece,  is  to  fill  the  buccal  side  with 
cement.  One  of  the  points  of  the  buccal  plate,  which  has  extended 
up  between  the  facings,  the  point  most  nearly  central  should  be 
used,  is  thrown  out  from  between  the  teeth  a  little,  suflficient  to 
allow  of  the  insertion  of  the  point  of  a  cement  syringe  (Fig.  (ill), 
and  oxyphosphate  of  zinc,  mixed  fairly  soft,  should  be  forced 
in  between  the  plate  and  the  saddle  and  facings,  tilling  the  space. 
The  cement  should  be  forced  in  until  it  can  be  seen  working  its 
way  out  at  both  the  mesial  and  distal  ends  around  the  necks, 
between  the  facings  and  the  plate.  While  th*-  cement  is  still  soft 
the  point  which  has  been  thrown  out  to  allow  for  the  entering  of 
the  syringe  point,  is  pushed  back  into  ])lace  between  the  facings. 

After  the  cement  has  hardened,  the  excess  should  be  cleaned  away 
from  around  and  between  the  teeth.  The  spaces  l)etween  the  teeth 
are  now  p;irti:dl,\  filled  in  with  gold,  a  plastic  gold  will  be  found 
bf^t  for  tlii^  purpose,  and  carried  «)\(T  tin-  jxtiiits  (tf  (he  plate  w  liidi 
extend   up  between  the  faring-.     The  ,-.paee>  should  be  filled  so  as 


334    PORCELAIN  CROWNS  AND  REMOVABLE  BRIDGE-WORK 

to  enable  them  to  be  smoothed  nicely  and  also  to  obliterate  any 
crevices  or  spaces  which  might  serve  as  a  lodgment  for  foodstuffs. 
The  fillings  are  then  smoothed  and  the  bridge  is  finally  polished. 


Fig.  611 

Polishing  the  Bridge. — A  felt  wheel  with  pumice  may  be  used 
over  the  surfaces,  which  it  has  been  necessary  to  grind,  but  over 
the  buccal  and  lingual  plates  a  fine  brush  wheel,  with  a  little  fine 
pumice,  may  be  used  for  just  a  moment.  Small  leather  wheels 
mounted  and  used  in  the  engine  can  be  used  in  the  small  places. 
After  the  bridge  has  been  washed,  the  rouge  is  applied.  This  can 
be  used  over  the  larger  part  of  the  bridge  on  a  felt  wheel,  but  over 
the  fluted  and  uneven  surfaces  of  the  plates  and  the  fillings  between 
the  teeth,  the  rouge  should  be  used  on  a  fine  brush  wheel,  and  the 
whole  polished  until  the  surface  is  smooth  and  highly  finished. 


SADDLE    BRIDGES.     ABUTMENTS    AT   BOTH   ENDS. 

Where  there  is  an  abutment  at  each  end  of  the  saddle,  the  bridge 
is  made  in  practically  the  same  manner  as  the  extension  bridges. 

In  the  anterior  part  of  the  mouth,  the  saddles  are  struck  up  and 
the  relation,  as  in  the  case  already  described,  of  the  saddle  with  the 
abutments,  is  secured  with  the  saddle  under  pressure.     Where  it 


SADDLE  BRIDGES—ABUTMEXTS   AT  BOTH  ENDS        '^',^h 

is  possible  to  do  so,  the  facings  are  ground  Hush  with  tlie  gum,  the 
saddle  coming  only  to  the  lingual  side  (Fig.  6 12),  but  where  there 
is  great  depth  from  the  gum  to  the  incisal  edge  of  the  teeth  and 
where  the  lip  is  long  and  it  is  not  possible  to  see  the  gum,  or 
where  greater  fulness  is  desired,  the  saddle  may  be  extended  over 


Fk;.  G12  Fig.  613 

the  ridge  and  made  in  practically  the  same  way  as  the  extension 
saddle  already  described,  a  labial  plate  being  swaged  and  fitted 
around  the  teeth  and  connected  to  the  saddle  as  are  the  buccal 
plates  to  the  saddle  previously  described  (Fig.  611^). 

The  facings  are  then  backed  and  soldered  in  the  usual  manner, 
and  the  lingual  sides  carved  and  finished  as  desired. 

There  are  cases  where  there  has  been  great  recession  and  shrink- 
age of  the  process  and  tissues,  when  it  may  be  necessary  to  use 
single  gum  teeth,  and  in  these  cases  the  teeth  are  ground  in  the 
usual  manner,  the  saddle  coming  in  contact  with  the  lingual  sides 
of  the  teeth. 

In  other  cases,  detachable  facings  ma\'  be  indicated,  the  gum 
contour  can  be  restored  by  building  out  with  porcelain  gum  body, 
and  the  whole  cemented  after  the  bridge  has  been  soldered  and 
completed,  but  no  rule  can  be  laid  down  covering  the  adaption  of 
these  different  styles  of  work,  each  must  be  decided  by  the  indi- 
vidual requirements  of  the  case. 


CHAPTER  XV. 
RETAINING  MEDIA. 

The  zinc  oxyphospliate  employed  in  the  setting  of  crowns  or 
bridges  should  possess  the  characteristics  which  would  recommend 
the  specimens  to  be  used  as  filling  material,  and  should  be  what 
is  known  as  a  hydraulic  cement.  It  should,  however,  flow  freely, 
and,  as  the  difficulty  of  maintaining  dryness  is  increased,  it  should 
set  promptly  and  yet  with  sufficient  deliberation  to  permit  of  the 
accurate  adaptation  of  the  crowns. 

The  operator  should  be  familiar  Avith  the  peculiarities  of  the  par- 
ticular cement  he  is  using,  as  specimens  of  the  different  makes  of 
oxyphosphate  differ  so  markedly  in  their  behavior,  that  it  is  unsafe 
to  use  them  for  this  purpose  without  having  first  tested  them. 

The  value  of  a  cement  depends  as  much,  perhaps,  upon  the 
manner  in  which  it  is  mixed  as  upon  the  kind  of  cement  which 
is  used.  The  cement  should  always  be  thoroughly  spatulated. 
A  little  of  the  powder  should  be  first  well  worked  into  the  liquid, 
a  very  little  of  it  being  dissolved  during  the  process.  The  powder 
is  then  added  a  little  at  a  time,  mixing  it  well  until  enough  has 
been  incorporated  to  give  it  the  desired  consistency  and  the  whole 
mass  is  perfectly  smooth  and  creamy. 

The  spatulas  used  should  be  strong  and  of  ample  size  to  do  the 
work  thoroughly.  Fig.  614  shows  a  spatula  suitable  for  single 
crowns  or  small  bridges,  but  for  large  bridges,  with  several  abut- 
ments, where  a  large  mix  is  required,  a  spatula  such  as  shown  in 
Fig.  615  or  one  even  larger,  is  indicated.  In  this  case  a  large  slab 
should  be  used.  A  piece  of  plate  glass  about  four  and  a  half  inches 
by  six  inches  will  answer  nicely  and  is  none  too  large. 

Setting  Crowns  with  Oxyphosphate  of  Zinc. — It  is  advisable  to  set 
all  pin  crowns  so  that  they  can  be  taken  off  without  mutilation,  if 
at  some  future  time  it  should  be  desirable  to  do  so  for  the  purpose 
of  repairing  them,  or  in  case  they  should  be  needed  as  anchorages 
for  a  bridge.  An  excellent  method  of  setting  them  so  that  they 
will  be  perfectly  rigid  and  at  the  same  time  be  easily  detachable,  is 
first  to  give  the  pin  and  the  inside  of  the  cap  and  band  a  thin  coat- 


CEMENTING  BRIDGES  IN  THE  MOUTH 


337 


ing  of  chloropercha.  A  convenient  way  to  do  this  if  a  solution  is 
not  at  hand,  is  to  take  a  fine  camel-hair  pencil,  dip  it  in  chloro- 
form and  then  rub  it  on  base-plate  jjutta-percha  and  paint  the  cap 
and  pin  with  this  extemporized  chloropercha.  The  solution  will 
dry  ^-ery  quickly  and  the  crown  is  then  set  in  the  regular  way,  with 
ox\phosphate  of  zinc.  If  at  any  time  it  is  desired  to  remove  the 
crown,  it  can  be  easily  done  with  a  pair  of  heated  forceps  or  pliers. 


I'lc;.  CI  1 


Via.  615 


CEMENTING    BRIDGES    IN  THE    MOUTH. 

In  nearly  every  case,  whether  a  bridge  l)e  fixed  or  removable,  it  is 
better  that  it  be  worn  in  the  mouth  without  cementing  for  at  least 
from  twenty-four  to  forty-eight  hours.  This  will  allow  it  to  adjust 
itself  and  settle  in  ])hu'e  and  render  the  cementing  of  the  piece  easier. 

Cementing  Fixed  Bridges. — After  the  bridge  has  been  worn  for  a 
time  and  removed  from  the  mouth,  it  is  first  thoroughly  cleansed. 
After  washing  well  with  soap  and  water  and  a  brush,  it  is  dried  and 
the  inside  of  the  abutment  caps  washed  with  nitric  acid,  after  whicii 
it  is  again  washed  with  water  and  dried  with  alcohol. 

The  abutments  in  the  mouth  are  then  cleansed  and  it  is  a  good 
plan,  especially  if  the  piece  has  been  worn  for  some  time  without 
cementing,  to  clean  them  first  with  pumice,  using  a  small  brush 
on  the  engine,  afterward  rinsing  the  mouth  well.  In  keeping  the 
mouth  dry,  napkins  are  preferre<l  to  cotton  rolls  as  the  latter  are 
.so  fibrous  that  some  of  the  fibers  may  make  their  way  over  the 
abutments  and  when  the  caps  are  cemented,  a  f<'w  fibers  might 
allow  for  the  entrance  of  moisture  and  so  escntually  cause  trouble. 
22 


338  RETAINING  MEDIA 

The  napkins  are  placed  so  as  to  keep  the  field  of  operations  as 
dry  as  possible.  The  teeth  and  canals  are  first  wiped  with  a  solu- 
tion of  bichloride  of  mercury  and  peroxide  of  hydrogen  and  dried 
off.  If  there  is  any  tendency  to  bleeding,  the  gums  may  be  wiped 
with  adrenalin  chloride.  They  are  then  washed  with  alcohol  and 
thoroughly  dried  again  with  hot  air  or  a  root  drier. 

Fig.  616  shows  the  Evans  root  drier.  It  consists  of  a  copper  bulb 
through  which  is  passed  a  silver  or  copper  point.  A  handle  is 
screwed  into  this  holding  the  point  firmly  in  place.  The  copper 
bulb  is  heated  in  the  flame  and  the  heat  is  transmitted  to  the  end 


Fig.  616 

of  the  point  which  is  placed  in  the  canal,  drying  the  root  out  quickly. 
A  fine  point  is  used  when  the  entire  canal  is  to  be  filled,  but  a 
heavy  one  can  be  used  to  dry  out  the  canal  where  a  crown  is  to  be 
placed  on  the  root. 

The  cement  is  now  mixed  and  if  the  canals  are  to  receive  a  post 
these  are  first  filled,  a  cement  syringe  is  here  indicated,  and  then 
the  caps  on  the  bridge  are  filled  full  of  cement  and  the  bridge  is 
pressed  firmly  in  position  in  the  mouth.  The  napkin  is  then  removed 
and  the  patient  is  instructed  to  close  the  teeth,  and  the  mouth  is 
carefully  examined  to  ascertain  that  the  bridge  is  in  its  proper 
position.  If  everything  is  all  right,  the  patient  is  told  to  keep  the 
teeth  closed  without  the  slightest  movement  of  the  jaws  and  this 
position  should  be  kept  for  at  least  ten  minutes.  Sometimes  it 
will  make  it  easier  for  the  patient  if  the  operator  or  his  assistant 
holds  his  hand  under  the  chin,  pressing  it  upward  during  the  setting 
of  the  cement.  At  the  end  of  from  twenty  minutes  to  one-half 
hour,  the  excess  cement  can  be  removed  from  around  the  edges  of 
the  caps,  the  gums  wiped  off  with  some  soothing  preparation  and 
the  patient  dismissed. ^  Another  appointment  should  be  made  for 
twenty-four  or  forty-eight  hours  later  when  the  mouth  should  again 
be  carefully  examined  to  see  that  everything  is  as  it  should  be. 

'  Campho-phenique  is  excfllent  for  tliis  purpose. 


CEMENTING  BRIDGES  IN  THE  MOUTH  339 

The  patient  may  again  lie  seen  a  couple  of  times  at  intervals  of  a 
week  or  two  before  being  finallx  ilismissed. 

Cementing  Removable  Bridges. — In  cementing  removable  bridges, 
the  work  is  done  in  practically  the  same  manner  as  in  the  case  of 
a  fixed  bridge.  The  piece  is  worn  for  a  time  and  when  removed 
is  thoroughly  cleansed,  the  inner  caps  being  removed  and  cleansed 
in  nitric  acid.  After  cleansing,  the  inner  caps  are  put  back  in  place 
in  the  bridge  and  film  of  pink  paraffin  and  wax  run  around  the 
edge  of  the  outer  caps  where  they  overlap  the  inner  caps.  It 
should  be  run  on  quite  hot  so  that  it  will  stick  well,  and  on  the 
anterior,  where  porcelain  crowns  or  facings  have  been  used,  the 
line  between  the  half-band  and  inner  caps  should  be  well  covered 
and  also  on  the  labial  side  between  the  outer  and  inner  floors. 
Great  care  must  be  used  not  to  get  any  of  the  wax  on  the  inside 
of  the  inner  caps.  If  this  happens,  it  must  be  carefully  removed 
before  cementing.  The  object  of  waxing  the  bridge  so  carefully 
in  this  manner  is  to  prevent  the  possibility  of  any  cement  working 
in  between  the  outer  and  inner  caps  and  so  making  a  fixed  bridge 
out  of  a  removable  one. 

The  bridge  being  thus  prepared,  the  remainder  of  the  work  of 
cementing  is  done  in  exactly  the  same  manner  as  for  a  fixed  bridge. 
After  cementing,  the  teeth  are  kept  firmly  closed  for  fifteen  or 
twenty  minutes  and  then  the  bulk  of  the  excess  is  removed,  but  it  is 
not  removed  from  around  the  gum  margin  at  the  edge  of  the  caps 
at  this  time.  The  patient  is  dismissed  and  another  appointment 
made  for  the  following  day  or  several  hours  later  the  same  day  when 
the  bridge  is  removed,  the  inner  caps  remaining  firmly  cemented 
to  the  abutments.  The  wax  and  excess  cement  is  now  carefully 
remo\'ed  from  around  the  caps  and  from  beneath  the  gum  and  the 
gum  wiped  with  camj)ho-phenique. 

The  patient  is  instructed  in  removing  and  replacing  the  bridge 
and  dismissed  with  instructions  to  remove  the  work  at  stated 
times  for  cleansing.  The  patient  should  be  seen  frequently  for  the 
first  few  weeks  to  see  that  everything  is  all  right.  They  should 
always  report  at  intervals  of  from  four  to  six  months  for  examina- 
tion and  by  so  doing,  the  work  can  be  watched  and  kept  in  jx'rfect 
condition  for  many  years. 

Cementing  Inlays  for  Removable  Bridges.  \\  licre  inlay  abutments 
are  used  as  attaclinicnts  for  r(in()\ablc  bridges,  the  inlays  are 
cemented  .sej)arately.  This  is  the  only  in.stance  in  removable  work 
where  the  parts  are  not  assembled  arifl  the  whole  treated  as  a  fixetl 


340  .  RETAINING  MEDIA 

bridge.  The  bridge  is  worn  for  a  time  without  cementing  and  then 
the  inlay  is  removed  and  thoroughly  cleansed  and  cemented  in 
place,  being  held  under  pressure  until  the  cement  has  hardened. 
The  excess  cement  is  then  trimmed  away  and  the  inlay  is  finished 
and  polished.  The  balance  of  the  bridge  is  then  treated  the  same  as 
a  fixed  bridge.  Wax  flowed  between  the  outer  and  inner  caps  and 
everything  cemented  in  place. 

The  reason  the  inlay  of  a  bridge  of  this  kind  is  set  separately  is 
that  there  is  only  one  way  for  it  to  go,  and  that  is  the  right  way. 
If  it  should- happen  to  be  twisted  the  least  bit  one  way  or  another, 
it  would  clear  the  margins  of  the  cavity  at  certain  points,  thus 
leaving  a  line  of  cement  exposed,  but  if  it  is  set  separately,  this 
can  never  happen. 


Fig.  617. — About  two-thirds  actual  size. 

The  cement  syringe  shown  in  (Fig.  617),  is  &  most  useful  aid  in 
cementing  crowns  or  bridges,  especially  where  several  pin  crowns, 
either  single  or  as  abutment  pieces,  are  to  be  set  at  one  time.  The 
syringe  consists  of  a  nickle-plated  brass  cylinder  or  barrel  with 
a  needle  or  tube  small  enough  to  enter  the  enlarged  canal,  and  a 
nickle-plated  brass  plunger.  There  is  an  opening  in  the  side  of  the 
cylinder  for  the  introduction  of  the  cement.  The  root  is  thoroughly 
dried  and  the  cement  mixed  to  the  consistence  of  thick  cream  and 
placed  in  the  cylinder.  The  piston  is  then  put  in  the  barrel  and  the 
end  of  the  needle  carried  to  the  end  of  the  canal  and  the  cement 
forced  into  it,  at  the  same  time  withdrawing  the  needle  slowly. 
In  this  way,  the  apical  extremity  of  the  canal  is  filled  first.  A 
number  of  roots  may  be  filled  in  this  manner  in  a  few  seconds  and 
there  will  be  ample  time  to  put  the  crowns  or  bridge  in  place  before 
the  cement  has  set. 

As  soon  as  the  piece  is  in  place,  the  syringe  is  plunged  into  a  basin 
of  cold  water  and  the  piston  worked  back  and  forth  to  free  it  from 
the  remaining  cement  while  this  is  still  soft.  It  is  also  well  to  rinse 
afterward  with  a  solution  of  bicarbonate  of  soda  so  that  any  remain- 
ing particles  of  cement  may  be  easily  removed.  If  the  cement  is 
too  hard  to  be  forced  out,  it  may  be  removed  with  the  drill  which 
comes  with  the  syringe  for  this  purpose. 


SETTIXa  CROWNS    WITH  GUTTA-PERCHA  .341 

SETTING    CROWNS    WITH    GUTTA-PERCHA. 

When  gutta-percha  is  to  be  employed,  it  is  necessan-  that  the 
several  parts  shall  be  at  a  temperature  which  will  permit" the  ready, 
deliberate,  and  accurate  adjustment  of  the  crown  and  gutta-percha 
to  the  root. 

The  crown  is  laid  ui)()n  a  gutta-percha  heater.  Dr.  How's  steatite 
slab  IS  useful  for  the  purpose  (Fig.  618),  or  in  the  absence  of  this 
appliance,  it  may  be  heated  over  a  small  alcohol  flame.  A  piece  of 
base-plate  gutta-percha  is  also  laid  on  the  slab,  or  heated  over 
the  flame  of  the  lamp,  and  when  soft  is  pressed  out  between  the 
fingers  into  a  sheet,  which  is  wrapped  around  the  heated  post. 


Fig.  618 


The  canal  is  moistenefl  so  that  the  crown  may  easily  be  removed 
and  the  crown  forced  on  to  the  root  as  far  as  possible.  It  is 
then  removed  and  the  surplus  gutta-i)ercha,  which  has  been 
squeezed  out  around  the  edge  of  the  band,  is  removed,  after  which 
the  canal  is  again  moistened  and  the  crown  heated  and  pressed 
into  place.  This  is  rcfjeated  until  the  crown  goes  up  to  its  normal 
position.  It  is  then  removed  and  cleansed  and  dried  with  alcohol 
and  a  very  slight  excess  of  gutta-percha  is  placed  around  the  pin. 
A  napkin  is  now  placed  in  position  to  keep  the  field  of  operation 
dry  and  the  canal  is  dried  thoroughly  and  then  wiped  out  very 
lightly  with  one  of  the  essential  oils,  preferably  eucalyptus.  The 
crown  is  now  again  licated  and  forced  up  into  place.  Any  excess 
of  gutta-percha  wliicli  may  have  been  squee/>ed  out  over  the  margins 
of  the  crown  is  removed,  and  the  work  is  completed. 

If  the  above  instructions  have  been  carefully  carried  out,  a  crown 
set  in  the  manner  described  will  be  as  permanent,  and  gi\-e  prac- 
tically as  goori  results  as  though  set  with  oxyphosphate  of  zinc  and 
at  the  sanu;  tinu;  possesses  tlu'  advantage  of  easy  removal,  should 
this  be  desin-d. 


CHAPTER  XVI. 

REPAIRING    CROWNS    AND    REPLACING   BROKEN 

FACINGS. 

Removing  Shell  Crowns. — When,  for  any  reason,  it  may  he  found 
necessary  to  remove  a  full  gold  crown  from  a  tooth,  if  the  crown 
has  been  properly  fitted  and  cemented,  it  will  generally  be  neces- 
sary to  cut  the  band  in  order  to  get  it  off.  This  may  be  easily  done 
with  one  of  the  crown  slitters  which  are  made  for  the  purpose,  as 
illustrated  in  Fig.  619.  With  one  beak  resting  on  the  cusp  and 
the  other  caught  under  the  gingival  edge  of  the  crown,  the  forceps 
are  closed,  dividing  the  band  all  of  the  way  to  the  cusp,  when 
by  giving  a  slight  rocking  movement,  the  crown  may  generally 
be  easilv  lifted  off.  Should  this  not  be  the  case,  an  instrument  is 
passed  under  the  flap  and  worked  around  the  tooth  to  loosen  the 
cement  and  the  band  gradually  worked  free  (Fig.  621).  A  hatchet- 
shaped  excavator  can  often  be  used  to  do  the  cutting,  the  blade 
being  repeatedly  drawn  from  the  cervical  edge  to  the  cusp,  until 
the  band  is  divided.  A  small  wheel  bur  will  do  tbe  work,  cutting 
from  the  cervix  to  the  cusp  in  the  same  way  as  with  the  excavator. 

One  of  the  best  instruments  for  use  as  a  crown  slitter  is  one 
which  was  not  designed  for  the  purpose.  This  instrument  is  the 
old  Physick  forceps,  used  in  the  extraction  of  lower  third  molars 
(Fig.  620).  The  edges  at  the  end  of  these  beaks  should  first  be 
sharpened  and  it  is  then  ready  for  use.  It  is  almost  universal  in 
its  application  and  either  beak  is  used  for  cutting.  One  of  the 
beaks  is  placed  on  the  occlusal  surface  of  the  crown  and  the  other 
over  the  gingival  edge  and  the  band  is  split  by  closing  the  forceps. 

Repairing  of  the  Shell  Crown. — In  repairing  the  shell  crowns,  the 
cement  is  first  thoroughly  removed  and  if  it  should  happen  to  be 
one  made  by  the  operator  and  a  sweated  crown  throughout,  the 
edges  can  be  brought  together,  a  small  strip  of  coin  gold  placed 
over  it  and  melted  in  place.  In  making  a  repair  of  this  character, 
the  crown  should  be  placed  on  a  piece  of  charcoal  with  the  cusp 
toward  the  operator.  The  flame  of  the  blow-pipe  is  then  thrown 
on  the  cusp  until  the  whole  crown  is  entirely  heated-up  nearly  to 


REPAIRIXC  OF   THE  SHELL  CROWN 


mm 

mm 


I'm:.  (il!» 


Via.  020 


344  REPAIRING  CROWNS  AND  REPLACING  BROKEN  FACINGS 

the  melting  point,  when  the  flame  is  flashed  across  the  break  and 
the  coin  gold  melted  over  it  (Fig.  622). 


If  it  is  a  soldered  crown  and  there  is  no  loss  of  material,  the 
edges  are  simply  brought  in  contact  and  solder  flown  over  it.     If 


Fig.  622 


there  has  been  much  loss  of  material  at  the  sides  of  the  cut,  a 
narrow  strip  of  thin  platinum  or  of  pure  gold  is  waxed  over  the 


Fig.  623 


Fig.  624 


line  of  division  on  the  inner  side  of  the  cap  which  is  then  filled 
with  investment  material,  dried  out  and  the  broken  part  covered 
with  solder  (Fig.  623). 


REMOVAL  OF  POST  345 

Removing  of  Porcelain  or  Porcelain-faced  Crowns. — The  remoxal  and 
repairing  of  a  porcelain-faced  crown  is  a  more  difficult  operation  than 
of  a  shell  crown.  If  the  crown  has  been  set  with  gutta-percha,  it 
may  be  easily  removed  by  grasping  it  with  a  heated  pair  of  pliers, 
or  forceps,  having  first  protected  the  lips  and  gums  of  the  patient 
with  napkins.  It  is  well  to  try  this  method  first  on  a  chance  of 
gutta-percha  having  been  used.  If  it  has  been  set  with  oxyphos- 
phate  of  zinc,  much  more  trouble  will  be  experienced  in  getting 
it  off.  It  will  be  necessary  first  to  separate  the  cap  from  the 
pin,  which  may  be  done  by  passing  a  drill  from  the  labial  side 
through  the  base  of  the  backing  at  its  junction  with  the  floor  of 
the  cap  to  one  side  of  the  pin  and  then  cutting  the  pin  through  with 
a  very  small  fissure  bur,  after  which  the  cap  is  easilv  pried  off  (Fig. 
624). 

Removal  of  Post. — 'J'here  is  on  the  market  an  instrument  designed 
for  removing  a  post  from  the  root  consisting  of  a  pair  of  jaws 
which  grasp  the  post,  while  another  pair  rests  against  the  end  of 
the  root.  When  the  pin  is  tightly  clamped,  a  screw  at  the  end 
of  the  instrument  is  turned,  and  if  the  post  is  not  ver\'  long  or 
has  not  been  well  cemented  it  can  be  removed  without  difficulty- 
(Fig.  625).     Where,  however,  the  pin  is  long  and  has  been  well 


Fk;.  62.^.      l>iii  Ic  uiiuit  post-puller. 

cemented,  it  will  be  necessary  first  to  cut  away  the  cement  from 
around  it  until  it  has  become  somewhat  loosened,  then  the  instru- 
ment may  be  used  to  remove  it. 

In  the  absence  of  one  of  these  instruments,  the  work  can  generally 
be  done  within  a  short  time  by  other  means.  The  cement  is  first 
l(M)sened  from  around  the  pin  with  a  very  fine  s|)ear-i)<)inted  drill. 
Th«'  shank  of  one  of  the  finest  burs  or  of  a  (Jates-CJliddcn  drill, 
flattened  on  two  sides  and  then  ground  to  a  sjiear  point  makes 
an  excellent  drill  for  the  purpose,  being  smaller  than  an.\  obtain- 
able at  the  dental  d<'{)ots.  The  cem(Tit  is  drilled  away  close  to 
the  [)in  all  around,  inclining  the  drill  toward  the  post  at  all  tim«'s 


346   REPAIRING  CROWNS  AND  REPLACING  BROKEN  FACINGS 

so  as  to  lessen  the  danger  of  a  perforation  or  a  possible  weakening 
of  the  root  by  cutting  into  it  (Fig.  620,  a  and  h). 

From  time  to  time  an  effort  may  be  made  to  loosen  the  pin  by 
grasping  it  with  a  pair  of  strong,  narrow-nosed  pliers  and  trying 


Fig.  626  Fig.  627 

to  rotate  it.  The  pin  roughing  and  bending  pliers  may  be  used 
for  the  purpose.  Very  often  the  nose  of  the  pliers  is  somewhat 
blunt,  but  it  may  easily  be  reduced  by  grinding  (Fig.  627). 

If  the  pin  does  not  loosen,  the  drilling  should  be  carried  deeper 
until  it  can  be  removed.  The  remainder  of  the  cement  is  then 
removed  from  the  canal  with  a  reamer  and  a  new  pin  fitted  to  it. 
The  palatal  portion  of  the  crown  with  the  backing  should  then 
be  cut  away  the  cap  placed  on  the  root  and  a  new  pin  waxed  in 
place.  The  cap  and  pin  are  now  removed,  invested  and  soldered, 
after  which  the  facing  is  ground,  backed  and  the  crown  soldered. 

REPLACING     BROKEN     FACINGS     ON     FIXED     CROWNS     OR 

BRIDGES  WITHOUT  REMOVING  THE  APPLIANCE 

FROM    THE   MOUTH. 

There  are  several  different  methods  of  replacing  a  facing  without 
removing  the  cap  and  pin  from  the  root.  A  good  way,  and  one 
which  makes  one  of  the  strongest  repairs  that  can  be  made,  where 
the  remaining  metal  portion  of  the  crown  is  of  sufficient  thickness, 
is  as  follows:  The  remnants  of  the  tooth  pins  are  first  removed 
and  ground  flush  with  the  backing,  and  an  impression  taken  cover- 
ing the  backing  and  floor  of  the  cap,  and  a  model  made  of  plaster, 
cement  or  Spence  metal.  A  hole  is  then  cut  in  that  face  of  the 
model  representing  the  backing,  against  which  the  new  facing  is 
to  be  fitted,  large  enough  for  the  pins  to  enter  freely  (Fig.  628). 
The  facing  is  then  selected  and  ground  to  fit  the  model  accurately. 
The  backing  of  the  crown  in  the  mouth  is  then  cut  out  to  accom- 
modate the  pins,  care  being  used  not  to  break  through  on  the 


REPLACIXa  BROKE X  FACINGS 


:U/ 


lingual  side.    The  cavity  is  tiien  deeply  undercut  all  around,  making 
it  strongly  retentive  in  shape  (  Fig.  029,  a,  b  and  r).    Fig.  (ioO,  a,  being 


/ 


Fig.  628 


Fig.  629 


Fig.  630 


Fig.  631 


a  horizontal  cross-section  of  the  backs.  The  pins  of  the  facing  are 
flattened  at  the  ends  and  bent  at  right  angles,  one  being  cut  a 
little  shorter  than  the  other  so  that  when  the  long  pin  is  inserted 
and  the  facing  pressed  as  far  to  that  side  as  it  will  go,  the  short 
pin  will  pass  through  the  opening  in  the  backing  (Fig.  630,  b). 
The  facing  is  now  removed  and  the  cavity  filled  with  cement,  and 
the  backing  and  floor  covered.  The  long  pin  is  first  introduced, 
the  facing  carried  to  that  side  until  the  shorter  one 
will  enter.  It  is  then  pressed  tightly  in  place  and  then 
forced  back  until  the  sides  of  the  facing  are  even  with 
the  backing.  This  will  bring  the  ends  of  both  the 
short  and  long  pins  under  the  ledge  of  the  cavity 
and  when  the  cement  has  hardened,  the  facing  will  be  so  firmly 
held  that  it  would  be  impossible  to  remove  it  except  by  breaking 
it  (Fig.  631). 

Another  method  of  repair  without  removal  from  tlie  mouth  is 
that  of  riveting  the  facing  to  the  backing.  This  is  one  of  the  oldest 
methods,  and  also  one  of  the  best  if  it  is  carefully  done.  The  pins 
are  cut  from  the  backing,  an  impression  taken  and  a  model  prepared 
as  in  Fig.  628.  The  new  facing  is  ground  to  fit  the  model.  A 
backing  of  heavy  tinfoil  or  paper  is  fitted  to  it  and  trinmied  care- 
fully to  the  edge  of  the  facing  all  around.  This  backing  is  then 
remcA'ed  and  fastened  in  position  over  the  gold  backing  of  the 
crown  in  the  mouth  (Fig.  6:»2).  The  holes  in  the  backing  will  show 
the  exact  position  of  the  pins  of  the  facing,  and  the  holes  may  be 
drilled  with  a  small  spear-pointed  drill  the  exact  size  of  the  pins. 
The  holes  are  then  countersunk  from  the  palatal  side  and  the 
pins  cut  oft"  so  that  they  will  i)roject  only  a  slight  (lisianre  through 
the  backing  CFig.  6.')3). 


348  REPAIRING  CROWNS  AND  REPLACING  BROKEN  FACINGS 

The  riveting  is  done  with  a  plate  punch.  The  facing  is  removed 
and  the  backing  and  floor  of  the  cap  covered  with  cement  of  about 
the  same  consistence  as  that  used  in  setting  a  crown  and  the  facing 


Fig.  632  Fig.  633  Fig.  634  Fig.  635 

placed  in  position.  A  piece  of  lead  or  a  thickly  folded  napkin  is 
placed  over  the  facing,  with  the  die  side  of  the  punch  resting  on 
this,  and  while  the  cement  is  yet  soft,  the  pin  is  riveted  by  rubbing 
and  burnishing  with  the  punch  end  of  the  forceps  until  the  counter- 
sink is  entirely  filled  (Fig.  634) .  After  riveting,  any  excess  platinum 
of  the  pin  may  be  ground  away  and  the  back  polished.  If  the  pins 
are  carefully  riveted,  and  the  holes  are  not  too  large,  this  makes  as 
strong  a  repair  as  can  be  made  by  any  method.  If  the  cement 
has  been  allowed  to  harden  before  the  riveting  is  done  it  will  be 
broken  and  will  crumble  away,  and  the  repair  will  not  be  as  satis- 
factory. 

Another  method  of  repair  is  as  follows:  The  headed  pins  are 
left  in  the  backing  (Fig.  635)  and  the  pins  of  the  facing,  which  is 
to  replace  the  one  broken,  are  ground  out  and  the  holes  dove- 
tailed. This  may  be  done  by  very  simple  and  easily  made  iastru- 
ments.  The  first  requisite  is  a  trephine  for  grinding  out  the  pins. 
This  can  be  made  by  using  the  shank  of  a  bur,  and  filing  it  down 
at  the  end  until  the  point  is  slightly  larger  than  the  tooth  pin 
(see  Fig.  636).  On  this  is  fitted  a  tube  about  one-half  inch  long, 
made  of  ordinary  brush  copper.  No.  36  gauge.  The  copper  is  cut 
about  one-half  an  inch  wide,  and  rolled  around  a  pin  or  mandrel 
about  the  size  of  the  tooth-pin.  It  is  rolled  around  twice  so  as  to 
form  a  tube  with  sides  doubled  the  thickness  of  the  metal  (Fig. 
637,  a).  The  end  of  the  bur  shank  is  then  inserted  into  one  end 
of  this  tube,  and  the  whole  fluxed  with  zinc  chloride  and  soldered 
with  ordinary  tinner's  solder  (see  Fig.  637,  h). 

Carborundum  and  glycerin  should  be  used  for  grinding.  The 
instrument  is  placed  in  the  engine  and  the  tube  dipped  in  the 
carborundum  and  glycerin,  and  then  placed  over  the  pin  and  the 


REPLACING  BROKEN  FACINGS 


:U9 


engine  started  (Fig.  638).  The  instrument  is  raised  and  lowored,  on 
the  facing,  as  it  revolves,  allowing  the  abrasive  powder  and  liquid 
to  constantly  work  under  it.  This  is  kept  up  until  the  pin  is  entirely 
ground  out.    After  the  pins  are  ground  out,  the  hole  is  dovetailed, 


Fig.  G3() 


Fi.i.  (J.17 


Fig.  638 


Fig.  039 


which  ma\'  be  done  1)\'  using  an  old  wheel  or  in\Trted  cone  bur 
from  which  the  temper  has  been  drawn.  This  is  dipped  in  the 
carborundum  and  glycerin  and  then  ])laced  in  the  hole  and  the 
engine  run  rapidly  until  the  hole  is  well  undercut  all  around  (Fig. 
639).  The  powder  is  then  well  washed  out  and  the  holes  filled  with 
cement.  The  backing  of  the  tooth,  which  has  previously  been  well 
dried,  is  covered  with  cement  and  the  facing  pressed  into  place  and 
held  there  until  the  cement  has  hardened  (Fig.  040). 


Fig.  64fl 


'J'liis  makes  a  quick  and  easy  repair,  but  where  great  strength 

is  refjuire<l   it   is  not  as  good  as  those  alread\-   mentioned,  as  the 

facing  has   i>een    weakened   to  a  certain   extent    by   enlarging  the 
pin-holes. 


350  REPAIRING  CROWNS  AND  REPLACING  BROKEN  FACINGS 

Dr.  Emory  A.  Bryant  has  a  novel  method  of  attaching  a  new 
facing.  A  tap  and  die,  the  size  of  the  tooth-pins  are  necessary, 
together  with  a  special  countersinking  tool  and  a  screw-driver.  The 
pins  are  cut  from  the  old  backing  and  holes  the  size  of  the  pins  of 
the  new  facing  are  drilled  in  proper  positions.  With  the  counter- 
sinking tool  held  in  a  right  angle  hand-piece,  the  holes  are  counter- 
sunk on  the  lingual  side  nearly  to  the  outer  wall  of  the  backing.  The 
nuts  are  made  to  correspond  in  size  and  taper  with  the  counter- 
sink. By  means  of  the  oiled  die,  a  thread  is  cut  on  each  pin  of 
the  facing,  and  continued  to  the  back  of  the  facing,  exercising  great 
care  that  the  pins  are  not  twisted  or  stained.  The  backing  is 
covered  with  cement,  the  facing  set  in  position  and  each  nut  is 
loosely  adjusted,  then  alternately  screwed  into  place  drawing  the 
facing  close  to  the  backing.  The  protruding  portions  of  nuts  and 
pins  are  then  ground  flush  with  the  backing  and  polished. 

This  method  of  replacing  broken  facings  is  very  ingenious  and 
will  answer  where  there  is  little  or  no  strain  on  the  facing,  but 
the  cutting  of  a  thread,  on  such  a  small  pin,  will  weaken  it  to 
such  an  extent  as  to  render  it  of  little  value  where  much  strength 
is  required.  It  is  better  if  the  full  strength  of  the  pin  can  be 
preserved. 


CHAPTER    XVII. 

BRIDGE-WORK  DPISIGXED  FOR  RIGCJVS  DISEASE 
CONDITIONS. 

By  HOWARD  T.  STEWART,  D.D.S., 

NEW   YORK   CITY. 

The  attachments  partially  illustrated  below,  is  the  outgrowth  of 
the  system  of  the  split  pin  and  telescope  crown  as  taught  by  Dr. 
Peeso  (in  his  construction  of  modern  removable  bridge-work),  to 
whose  teachings  I  owe  my  early  inspiration. 

On  studying  closely  the  crowns,  we  will  see  that  the  original 
idea  of  the  split  pin  and  telescope  crown  obtains  through  the  entire 
work.  Even  the  split  bar  is  the  suggestion  of  the  split  pin,  and 
the  "shoulder  crowns"  are  a  modification  of  the  telescope  crown. 

This  system  was  gradually  worked  out  by  the  writer,  in  his 
efforts  to  adapt  bridge-work  to  those  conditions  of  alveolar  inflam- 
mation where  special  care  is  required  to  produce  permanent  results. 

As  my  own  work  differs  to  a  certain  extent  as  to  the  individual 
lines  above  referred  to,  from  any  other  system,  I  am  giving  this 
in  addition  to  what  Dr.  Peeso  has  already  presented,  in  the  hope 
of  having  it  contribute  somewhat  to  this  characteristic  individuality. 

Fig.  041  illustrates  attachments  made  of  telescoijcs  and  split 
bars,  also  an  adjustable  saddle.  This  saddle  is  attached  temporarily 
with  gutta-percha  or  cement,  removed  and  lowered  as  absorption 
of  the  ridge  takes  place.  This  prevents  rocking  of  bridge  and 
leverage  on  roots. 

Fig.  042  is  a  full  upper  with  rubber  saddles.  These  saddles  arc 
sometimes  made  of  rubber  (always  perfectly  smooth  and  highly 
polished  next  to  the  gum),  and  as  the  ridge  absorbs,  wax  is  added, 
patient  bites  on  it  and  more  rubber  is  added.  This  can  be  repro- 
ducer! in  gold  later. 

The  cuspid  shows  the  usual  tube  in  canal  with  a  short  tube  swung 
off  that  just  clears  the  gum.  This  makes  a  firmer  locking  device 
than  the  one  pin. 

Tlic  (•(•ntnil  is  llic  nsn;il  lube  Nhglitly  Iciigt  linn  d  up  into  (lie 
b(»d\'  ()\  rruwii. 


352         BRIDGE-WORK   DESIGNED  FOR  RIGG'S  DISEASE 


Fig.  641 


Fig.  642 


BRIDGE-WORK  DESIGNED  FOR  RIGG'S  DISEASE         353 

The  first  hicuspkl  tube  extends  well  into  the  erowii,  giving 
longer  pin  and  additional  strength  and  friction. 

The  second  bicuspid  shows  one  tube  in  the  canal  and  one  short 
tube  stopping  at  the  cap,  this  last  tube  being  the  length  only  of 
the  box  in  the  crown. 


Fio.  G4:i 


Fig.  043  is  a  case  often  |)rcsenting  itself  cs[)ccialiy  in  Kigg's 
disea.se  mouths.  Here  the  important  feature  is  the  palatal  bar. 
The  writer  was,  so  far  as  he  knows,  the  first  to  utilize  these  l)ars 
in  bridge-work.  After  years  of  experiment,  he  finds  the  proper 
place  for  these  bars  to  be  very  far  back  usually  near  the  junction 
of  the  .soft  and  hard  palate.  There  is  no  m<'clianical  advantagt; 
in  placing  these  forward  (as  is  usually  donr)  not  pos.sessed  by  those 
placed  well  back  and  here  tlie\'  do  nol  interfere  with  the  1()ngu<; 
when  properly  ((instructed.  Note  liow  in  mastication  this  bar 
2.'} 


354         BRIDGE-WORK  DESIGNED  FOR  RIGG'S  DISEASE 

overcomes  leverage  in  three  different  directions,  and  it  is  at  once 
apparent  how  very  useful  it  would  be  where  the  alveolar  process 
about  the  abutments  was  partially  absorbed.  This  bar  is  made 
by  flowing  20-carat  solder  on  pure  gold.  The  solder  naturally 
assumes  a  rounded  shape  approximating  a  proper  form  next  to  the 
tongue.  The  lower  bar  is  shaped  thick  at  the  bottom  (to  give  it 
rigidity  and  so  as  to  be  rounded  and  blunt  to  the  frenum),  and 
thin  at  the  top  so  as  not  to  be  noticed  by  the  tongue.  Rigidity 
is  extremely  important  to  overcome  the  leverage  in  both  upper 
and  lower  bars.  The  first  bicuspid  in  Fig.  643  shows  two  short 
tubes  neither  of  which  enter  the  canal.  Room  is  left  for  the  por- 
celain on  the  buccal  side  of  the  caps. 


Fig.  644 


Fig.  644  shows  a  case  where  all  but  seven  teeth  were  lost  from 
Rigg's  disease.  It  will  be  noted  that  in  this  case  (as  in  all  the 
others)  each  abutment  stands  alone — no  two  are  fastened  together. 
In  this  way  when  the  bridge  is  removed,  a  silk  thread  can  be  carried 
all  around  each  abutment,  beneath  the  gum;  and  this  is  important 
to  prevent  a  return  of  peridental  troubles.  Each  tooth  also  gets 
some  individual  motion  in  brushing  and  massaging. 

The  molar  and  bicuspid  on  the  right  show  a  modification  of  the 


BRIDGE-WORK   DESIGNED   FOR   RK.'G'S   DISEASE         355 

same  attachments  shown  in  Fiys.  ()42  and  04;).     These  are  longer 
and  present  more  friction. 

The  bicuspid  on  the  left  shows  another  form  of  the  split  bar. 
It  is  not  really  a  split  bar,  but  two  pieces  of  clasp  metal  soldered 
to  a  boxing  at  opposite  ends.  That  is  where  one  clasp  metal  bar  is 
soldered,  the  other  bar  is  a  loose  end.  In  other  words,  where  in  the 
other  attachment  the  two  pieces  of  clasp  metal  are  soldered  together 
at  the  same  end  of  the  boxing,  these  are  soldered  separately  in  the 
boxing  at  opposite  ends.  P^ach  end  of  the  boxing  thus  having 
one  piece  of  clasp  metal  soldered  to  its  wall. 


Fi(i.  045 


Fig.  ()44  shows  two  small  tubes  swung  off  tiic  side  of  a  crown. 
These  can  be  used  where  it  is  desirable  to  place  the  attachment 
on  the  side  of  a  crown  instead  of  within  it.  One  tube  is  sometimes 
sufficient.     This  may  be  attached  to  inlays. 

The  dummy  shows  four  si)lit  pins  to  fit  the  foiu-  tubes  soldered 
tf)  the  two  adjoining  crowns. 

The  molar  in  Fig.  (■»4(1  is  the  strongest  of  all  attachnicjits  the 
writer  has  devised.  Its  chief  application  is  in  the  upper  arch 
where  the  bite  is  very  short  and  where  much  of  the  bridge  has  to 
be  supported  by  this  single  attachment.  In  this  single  crown 
it  looks  bulky  but  in  a  bridge  this  extension  is  incorporated  into 
the  dummy  adjoining.  Note  the  reinforcement  of  the  clasp  metal 
at  tlx-  soldered  ends  to  give  it  additional  strength. 

The  bicuspid  shows  how  this  split  bar  may  be  used  when  the  end 
of  a  bridge  is  on  a  bicusj)id  root  that  w  ill  not  receive  a  tube.  The 
cus[>id  shows  attaclnneni  much  like  tli.if  of  the  left  bicusf)id  in 
Fig.  HH. 

The  bicuspid  on  the  left  side  of  I''ig.  (Ill  .-ln»\\>  t  lie  ;it  laclunenl 
extcn<ling  off  both  sides  <'(|ually.  Here  was  needed  a  large  friction 
surface.  This  attachment  dill'ers  from  all  the  others  in  that  instead 
of  having  the  two  pieces  of  e|;l^p  metid  free  at  the  same  end,  they 


356 


BRIDGE-WORK  DESIGNED  FOR  RIGG'S  DISEASE 


are  free  at  opposite  ends.  Thus  where  one  is  free,  the  other  is 
soldered.  This  gives  a  more  equal  pressure  all  along — not  as  the 
other  bars  do  or  as  a  split-pin  does. 

The  writer  originated  this  form  of  attachment  (the  "split-bar") 
and  has  been  demonstrating  it  at  dental  conventions  in  its  various 
forms  for  about  nine  years.  It  is  capable  of  a  great  variety  of  forms 
and  applications.  The  original  mechanical  principle  of  this  bar  is 
the  same  as  the  split-pin  as  taught  by  Dr.  Peeso. 


•^ 


Fig.  646 


This,  system  in  its  present  form  was  gradually  evolved  to  be 
especially  adapted  to  Rigg's  disease  conditions,  but  is,  of  course, 
equally  applicable  to  any  condition. 

On  studying  these  attachments  closely  one  will  see  an  astonish- 
ing amount  of  friction  surface  presented — the  two  pieces  soldered 
to  the  cap  being  entirely  boxed  in  beside  the  clasp  metal  running 
between.  One  end  of  the  bar  is,  of  course,  free,  alloM^ng  the  two 
pieces  to  be  spread  just  as  the  split  pin  is. 

Space  here  forbids  a  detailed  account  of  the  construction  of  the 
various  forms  of  these  attachments,  each  of  which  must  be  adapted 
to  the  needs  of  the  individual  case. 


CHAPTER   XVIII. 

DENTAL  METALLURGY.! 

(loLD  WD  ns  Ali.oys,  Including  Refractohy  Materials 
AND  Fluxes. 

By  Louis  J.  Weinstein. 

In  the  preparation  of  this  contribution,  it  has  been  the  aim  of 
the  author  to  present  a  brief  and  practical,  rather  than  an  academic 
discussion  of  the  subject. 

In  addition  to  a  consideration  of  the  gold  alloys,  it  was  found 
ad\isable  to  include  a  section  on  the  closely-allied  and  important 
subjects  of  refractory  materials  and  fluxes  used  in  connection  with 
gold,  during  soldering  or  casting  operations. 

The  series  of  investigations,  upon  which  this  contribution  is 
based,  was  started  during  the  year  1908,  when  in  attempting  to 
use  the  coin  gold  and  modifications  of  same  in  the  form  of  solders, 
he  was  seriously  handicapped  by  the  comparatively  low  melting 
point  of  the  coin  gold,  and  the  inadequacy  of  the  other  gold  alloys 
usually  ol)tainable,  which,  to  the  man  of  exceptional  ability,  is  not 
so  apparent  as  to  one  of  average,  or  even  less  than  average  skill. 

In  \iew  of  the  well-known  fact  that  platinum  is  a  metal  that 
could  be  alloyed  with  gold  to  increase  the  melting  i)oint  of  the 
latter,  a  number  of  experiments  were  ma<le  to  produce  a  fornnila 
for  a  gold  alloy  sufficiently  high  in  melting  point,  so  that  the  general 
practitioner  could  use  it  as  a  sul)stitute  for  coin  gold,  and  therein 
(eliminate  the  process  of  "sweating,"  and  instead,  solder  the  result- 
ant high-fusing  gold  witli  other  gold  of  a  melting  point  ((inal  to 
that  of  24-  or  22-K.  and  thus  obtain  a  strong  union  that  wonid 
withstan<l  tl)e  subscfjuent,  and  often  numerous,  soldering  opera- 
tions required  for  the  completion  of  the  case. 

The  alloys  finally  developed  were  found  so  satisfactory,  that 
it  is  not  too  much  to  say  that  even  in  the  hands  of  the  skilled 
oiK'rator  these  alloys  will  prove  of  considerable  value,  if  for  no 
(»ther  reason  than  the  very  great  differenee  in  the  melting  |)oiftt 

'  Copyritrlil   M)Hi,  Ijy  Loiii.s  .1.  Wi-inslcin.      All  rinlilK  rcHcr\ci|. 


358  DENTAL  METALLURGY 

between  the  highest  and  lowest  fusing  alloys  in  the  series,  and 
the  consequent  increased  facility  and  safety  during  the  necessary 
subsequent  soldering  operations. 

In  the  author's  efforts  to  obtain  information  from  which  to  for- 
mulate alloys,  he  was  greatly  handicapped,  inasmuch  as  there  were 
no  dental  publications  bearing  to  any  extent  on  the  subject.  After 
a  thorough  study  of  the  then  recently  revised  books  on  dental 
metallurgy,  a  number  of  experiments  were  made,  the  results  of 
which  did  not  appear  to  correspond  with  the  data  in  the  text-books. 
A  number  of  works  on  general  metallurgy  were  consulted,  and 
found  to  differ  materially  with  the  dental  text-books  in  a  great 
many  instances,  particularly  on  data  concerning  the  behavior  of 
the  binary  alloys  of  gold  and  silver,  gold  and  platinum,  etc.  In 
order  to  establish  a  definite  foundation  upon  which  to  base  further 
researches,  the  author  proceeded  to  make  a  series  of  binary  alloys, 
and  from  the  resultant  data  was  enabled  to  proceed  with  the 
development  of  more  complex  alloys. 

The  resultant  formulae  given  herein  have  been  in  practical  use 
for  a  period  ranging  from  three  to  six  years,  and  while  the  author 
does  not  claim  that  his  is  by  any  means  the  last  word  on  the  sub- 
ject, he  trusts  that  the  results  of  his  research  will  prove  of  some 
immediate  benefit  to  both  advanced  students  and  practitioners. 

The  author  takes  this  opportunity  of  thanking  Drs.  Edwin  W. 
Harlan,  Frederic  A.  Peeso,  James  H.  Prothero,  William  S.  Prensky, 
Mr.  Harry  C.  Ney  and  other  friends  for  their  kind  encouragement 
and  aid. 


GOLD  AND  ITS  ALLOYS 


359 


TABLE  Xo.  I.— THE  MELTING  POINTS'  AND  DENSITIES  OF  METALS. 


Name  of  metal. 
GOLD 

Symbol. 
Au 

Melting 
point,  °  F. 

1945 

Melting 
point,  °  C. 

1063 

Density. 
19.3 

Gboup 

I.— Silver 

Ag 

1761 

960 

10.5 

Copper 

Cu 

1981 

1083 

8.9 

Platinum 

Pt 

3190 

1755 

21.5 

Palladium 

Pd 

2820 

15.50 

11.4 

Group 

II. — Iridium 

Ir 

4170 

2300 

22.5 

Osmium 

Os 

4900 

2700 

22.5 

Rhodium 

Rh 

3525 

1940 

12.1 

Group 

III.— Zinc 

Zn 

787 

420 

7.1 

Cadmium 

Cd 

610 

.321 

8.6 

Tin 

Sn 

450 

232 

7.3 

Aluminum 

Al 

1218 

658 

2.7 

Group 

IV.— Nickel 

Ni 

2646 

1452 

8.9 

Cobalt 

Co 

2714 

1490 

8.7 

Manganese 

Mn 

2237 

1225 

7.4 

Chromium 

(> 

2750 

1510 

6.9 

Tantalum 

Ta 

5160 

2850 

14.5 

Tungsten 

W 

5430 

3000 

18.7 

Molybdenum 

Mo 

4500 

2500 

8.6 

Vanadium 

V 

3150 

1730 

6.1 

Titanium 

Ti 

3450 

1900 

4.5 

The  elements  following  gold  have  been  divided  into  four  groups. 
This  division  is  an  arbitrary  one,  and  made  solely  for  the  purpose 
of  facilitating  future  references. 


•  The  melting  points  are  afcording  to  the  latest  data  i)ul)li.shed  by  the  l'.  S.  Hureau 
Standard.s. 


360  DENTAL  METALLURGY 


BINARY   ALLOYS. 


It  is  a  well-known  fact  that  pure  gold  has  but  a  limited  use  in 
the  construction  of  various  dental  appliances,  and  that  it  is  neces- 
sary to  alloy  it  with  various  other  metals,  in  order  to  increase  its 
durability,  hardness,  and  tenacity,  and  to  vary  the  melting  point 
above  or  below  that  of  pure  gold,  as  may  be  required.  The  metals 
in  common  use  for  this  purpose  have  been  copper,  silver,  and 
platinum,  the  latter  to  a  limited  extent,  also  zinc,  cadmium,  etc., 
for  solders,  which,  of  course,  require  a  considerably  lower  melting 
point  than  the  gold  upon  which  they  are  to  be  used. 

A  thorough  knowledge  of  the  properties  of  the  simple  binary 
alloys  is  of  paramount  importance,  because  these  properties  almost 
invariably  give  an  indication  of  what  may  be  expected  from  more 
complex  alloys. 

It  is  generally  accepted  by  metallurgists  that  binary  alloys  of 
gold  and  silver,  copper,  platinum,  or  palladium,  form  solid  solutions, 
that  is,  solutions  of  one  metal  in  another,  if  in  proportions  within 
certain  limits.  Such  binary  alloys  as  will  be  discussed,  form  solid 
homogeneous  solutions,  except  when  otherwise  noted. 

It  is  unnecessary  to  enter  into  an  academic  discussion  of  the 
possible  molecular  affinity  existing  among  various  elements  or 
of  eutectics,  formed  between  the  metals  in  the  binary  alloys  that 
will  be  considered,  because  such  compounds  or  mixtures  do  not 
occur  in  such  alloys  as  may  be  considered  fit  for  use  in  the  mouth. 
For  example,  alloys  of  gold  and  copper  in  the  proportion  of  82 
per  cent,  gold  to  18  per  cent,  copper  form  a  eutectic  which  is  the 
lowest  fusing  of  the  gold  copper  series,  and  when  more  than  18 
per  cent,  copper  is  present,  the  copper  is  not  in  uniform  solution 
and  segregates.  As  the  alloys  containing  over  15  per  cent,  copper 
are  extremely  brittle  and  ununiform,  no  binary  alloys  containing 
more  than  10  to  12  per  cent,  copper  will  be  considered.  In  other 
words,  alloys  of  gold  and  copper,  where  copper  does  not  exceed 
12  or  13  per  cent.,  do  not  form  any  compounds  with  special  charac- 
teristics. 

To  simplify  the  references  to  ternary,  quaternary,  or  more 
complex  combinations  of  metals,  alloys  of  two  metals  will  be 
termed,  as  is  customary,  "binary,"  but  the  alloys  composed  of 
three  or  more  metals  will  be  termed  "complex"  alloys. 

Gold  and  Silver. — Silver  is  commonly  utilized  as  an  alloying 
element  with  gold.    It  is  used,  to  a  considerable  extent,  as  part  of 


BINARY   ALLOYS  -  361 

tlie  aik»y  in  dental  gt)l(ls,  and,  as  will  be  shown  later,  principally 
as  a  eheai)ening  agent. 

There  seems  to  prevail  generally  an  erroneous  opinion  regarding 
the  properties  of  silver-gold  alloys.  It  has  been  stated^  that  silver 
is  used  to  harden  and  lower  the  melting  point  of  gold.  This  deduc- 
tion is  distinctly  contrary  to  the  results  obtained  by  the  author. 
After  making  a  number  of  binary  alio}  s,  it  was  proved  that  even 
the  maximum  percentage  that  may  be  used  in  dental  work,  say 
25  per  cent,  of  sih'er  to  75  per  cent,  of  gold,  does  not  confer  any 
perceptible  hardness  upon  the  gold,  neither  does  it  lower  the  melting 
point  to  such  an  extent  that  the  difference  could  be  measured  with 
a  pyrometer. 

Practically  the  only  effect  silver  (even  if  present  to  the  extent 
of  25  per  cent.)  has  upon  gold,  is  to  discolor  the  gold,  making  it 
greenish,  and  lower  the  specific  gravity,  thus  increasing  the  volume. 
It  will  thus  be  seen  that  silver  confers  no  special  benefit  upon  gold, 
except  cheapening  it  and  acting  as  a  color  modifying  agent.  On 
the  other  hand,  it  may  prove  detrimental,  as  a  considerable  propor- 
tion of  silver  may  interfere  with  the  action  of  other  alloying  elements 
when  attempting  to  produce  si  complex  gold  alloy,  and  also  on 
account  of  the  strong  affinity  that  oxygen  and  other  gases  possess 
for  silver.  It  will  thus  be  readily  seen  that  small  percentages  may 
sometimes  be  used  to  advantage  as  a  color-modifying  agent,  but 
a  large  percentage  of  silver  is  distinctly  contraindicated. 

Silver,  in  such  proportions  as  may  be  needed  for  dental  golds, 
alloys  uniformly  and  without  difficulty,  and  may  be  depended  upon 
to  remain  in  uniform  distribution. 

The  author  has  found  that  gold  alloys,  with  a  high  percentage 
of  silver,  when  remelted  and  cast,  show  in  the  casting  a  consid- 
erable variation  of  the  silver  content  which  indicates  that  a  jiartial 
separation  takes  place.  This  has  not  been  investigated  further 
for  tlie  reason,  that  castings  of  gold  with  a  high  percentage  of 
silver  have  no  practical  application.  As  stated  before,  small  i)er- 
centages  of  silver  have  ])racti(ally  no  effect  upon  the  gold  and 
this  fact  has  been  taken  advantage  of,  for  a  considerable  period  of 
time,  by  at  least  one  manufacturer,  who  alloys  pure  gold  with  from 
1  to  2  per  cent,  of  silver,  and  sells  it  as  24-I\.  This  alloy  appears 
•SO  similar  to  pure  gold  that  the  ordinary  eye  is  decei\ed  and  the 
unprincipled  manufacturer  is  the  gainer. 

'  IvHwiK'n  MctalluFKy  (Kofiiig'.i  rcv'itiion),  \t.  Ili.'i;  (loiliicn'.-i  Mclalliiiny  ( Milhfiry'.s 
rovi.-iioii),  ]>.  278. 


362 


DENTAL  METALLURGY 


Fig.  647  illustrates  the  melting  point  curve  of  gold  silver  alloys. 

Practically  the  same  determination  appears  in  very  recent  works 
on  metallurgy.^ 

Silver-platinum  alloys  have  been  used,  to  a  considerable  extent, 
for  crown  posts,  dowels,  backings,  etc.  As  a  rule,  alloys  of  this 
character  (20  to  30  per  cent.  Pt.)  are  extremely  unsatisfactory, 
both  during  their  manipulation,  and  in  ultimate  service,  and  their 
use  should  be  avoided.    They  are  somewhat  improved  with  higher 


Fig.  647. — Melting  Points  of  Alloys  of  Gold  and  Silver. 


2050 


2000 


1950 


1900 


1850 


1T50, 


~^' 

^-. 

»^ 

N 

\ 

N 

\ 

\ 
\ 

'  0     10     :»     30    40     50     80     70     80    90    100 
Percentage  of  Silver. 


5  per  cent.  Ag,  melting  point  1945°  F.,  1063°  C. 
10  "        Ag,         "  "      1945°  F.,  1063°  C. 

15  "        Ag,         "  "      1943°  F.,  1062°  C. 

30  "        Ag,         "  "      1942°  F.,  1061°  C. 

percentages  of  platinum  or  palladium,  but  the  alloys  are  extremely 
ununiform  and  still  quite  soluble  in  acids  and  apt  to  discolor  and 
corrode.  The  cost  with  more  platinum  is  considerably  higher  and 
even  then  the  alloys  are  not  equal  to  a  fair  grade  of  alloyed  gold, 
either  in  usefulness,  or  economy. 

Gold  and  Copper. — Copper  is  one  of  the  most  commonly  used 
and  most  useful  alloying  elements.  It  confers  hardness  and  elasticity 
upon  gold,  but  is  detrimental  when  used  in  large  proportions,  on 
account  of  its  great  tendency  to  lower  the  melting  point  of  the 
alloy,  and  the  strong  oxidation  and  brittleness  of  the  alloys. 
The  copper  is  in  high  proportion.     It  is,  however,  a  most  useful, 

1  Fenchel's  Metallurgy. 


BINARY  ALLOYS 


363 


aiul  in  fact  an  iiidispcihsdhU'  alloying  element,  if  employed  judi- 
ciously. Alloys  of  gold  and  copper,  such  as  U.  S.  coin  gold  (An. 
90-  Cu  10),  ha^•e  been  used  with  most  satisfactory  results  both 
from  the  standpoint  of  durability  and  resistance  against  the  oral 
fluids.  An  alloy  of  this  character  is  ideal  for  crown  work,  except 
for  the  disadvantage  of  its  low  melting  point,  which  is  caused  by 
the  copper  content  and  its  range  of  usefulness  is  therefore  limited, 


Fig.  648. — Melting  Points  of  Alloys  of  Gold  and  Copper. 


aooo 


lavi 


1900 


1850 


1750 


1700 


1650 


1600 


/ 
/ 

\ 

/ 

/ 

\ 

/ 

/ 
/ 

\ 

\ 

/ 

/ 

\ 

/ 

y 

\ 

y^ 

:«)         to         :*)        m 
Percentage  of  Copper. 


00 


100 


5  per  cent.  Cu,  mcltinK  point  1S40°  F.,  1004°  C. 
10  "        Cu,         "  "      1735°  F.,    1)46°  C. 

15  "        Cu,         "  "      1690°  F.,    921°  C. 

18  '•        Cu,         "  "      1661°  F.,    90.5°  C. 


even  in  the  hands  of  the  skilled  operator.  This  inadequacy,  as  will 
be  shown  later,  can  be  corrected  by  sub.stituting  platinum,  etc., 
for  some  of  the  copjxT,  thus  raising  the  melting  j)()int,  and  reducing 
oxidation,  without  changing  the  valuable  properties  the  coin  gold 
possesses;  namely,  strength  and  durability. 

Fig.  (548  illustrates  the  melting  point  curve  of  gold-copixT  alloys. 
As  will  be  seen  from  the  chart,  the  melting  point  of  pure  gold  drops 
rapidly  upon  the  addition  of  copper;  .">  |)cr  cent,  copper  lowers  the 
melting  point  ab(»u1   100'^  |'\;  10  |)er  cent.  co|)|)er  lowers  tlie  melting 


364  DENTAL  METALLURGY 

point  of  gold  about  200°  F.;  15  per  cent,  copper  lowers  the  melting 
point  about  250°  F. ;  and  18  per  cent,  causes  a  drop  in  melting  point 
of  about  300°  F.  As  will  be  seen  from  the  illustration,  the  lowest 
melting  point  between  gold  and  copper  is  when  18  per  cent.  cu.  is 
present.  The  addition  of  more  than  18  per  cent.  cu.  causes  a  rise 
in  melting  point  until  the  melting  point  of  copper,  1980°  F.  is 
reached. 

x\s  mentioned  previously,  it  is  advisable  to  limit  the  total  copper 
content  to  10  or  12  per  cent.  Consequently,  if  the  melting  point 
of  an  alloy  of  gold  and  copper  of  requisite  strength  and  hardness 
is  too  low,  it  is  necessary  to  use  platinum  or  palladium  to  bring  it 
to  the  point  desired. 

The  valuable  properties  of  copper  as  a  hardening  agent  have 
apparently  been  underestimated,  and  not  given  sufficient  considera- 
tion by  writers,  but  taken  advantage  of  by  manufacturers,  as  will 
be  noted  in  the  composition  of  commercial  clasp  metals. 

Gold  and  Platinum. — Platinum  is  being  used  to  some  extent 
as  an  alloying  element  with  gold,  principally  for  clasp  metal,  etc. 
It  has  been  stated  that  platinum  confers  great  elasticity  and  hard- 
ness upon  gold,  which  appears  correct  only  to  a  limited  extent. 
The  author's  experiments  have  indicated  that  platinum  has  com- 
paratively little  effect  as  a  hardening  agent  upon  gold.  It  does, 
however,  raise  the  melting  point  considerably,  as  will  be  shown 
later. 

Platinum  is  much  inferior  to  copper  as  a  hardening  agent.  This 
is  readily  proven  upon  an  examination  of  a  binary  alloy  of  gold  and 
copper  containing  10  per  cent,  copper,  and  a  binary  alloy  of  gold 
and  platinum  containing  25  per  cent,  platinum  (so-called  platinum 
solder).  A  comparison  of  two  pieces  of  equal  dimension  will  show 
that  the  gold-copper  alloy,  with  10  per  cent,  copper  is  quite  as 
hard  and  elastic  as  the  gold  alloy  with  25  per  cent,  platinum,  and 
more  uniform.  It  is  therefore  evident  that  platinum  is  not  the 
most  suitable  hardening  agent,  and  its  range  of  usefulness  as  an 
alloying  element  is  therefore  limited. 

Platinum,  however,  is  an  excellent  adjunct  to  copper,  as  it  tends 
to  raise  the  melting  point,  which  is  lowered  sensibly  by  any  con- 
siderable percentage  of  copper. 

Fig.  649  illustrates  the  melting  point  curve  of  gold-platinum 
alloys. 

Large  percentages  of  platinum  cannot  be  alloyed  uniformly  with 
gold,  and  in  order  to  insure  a  uniform  alio}',  it  is  not  advisable  to 


BIXARY   ALLOYS 


865 


use  more  than  .")  to  10  per  cent,  in  a  binary  alloy  and  10  to  lo  per 
cent,  in  a  complex  alloy.  In  the  latter,  the  other  alloying  dnueuis 
help  to  hold  the  ylatimnn  in  uniform  distribution.  If  it  is  desired 
to  raise  the  melting  point  of  an  au,-cu.  alloy  higher  than  5  to  10 


Fig.  649. — Melting  Points  of  Alloys  of  Gold  and  Platinum. 

•z'm 


zm 


2100 


2J50 


2300 


2:ij0 


2:A)0 


21.)0 


2100 


2(i.>() 


2t)iK) 


I'.XK) 




-^ 

y 

• 

/■ 

1 

III         ;.'o         :jo  III  .-,1 

I'crccntufjc  of  I'lutiniun. 


.")  pcrcciil.  I'(,  iiiclliim  poiiil  2U\')°  !•'.,  I  102°  C. 

10           "  I'l,          ••  "  20S0^'  F.,  1141°  C. 

1''        ■'  I't.       "  •■  iiior>°  F.,  ii(irj°  c. 

^"           "  I't.          "  "  22«0°  F.,  122S°  C. 


per  cent,  plalinuni  makes  possible,  il  is  ad\  isahlc  to  use  ixdhuliuni, 
which  cotuhines  jjerfectji/  in  l.otji  the  liiimrx  and  complex  alloys  that 
will  l)c  consirlcrcd. 


366 


DENTAL  METALLURGY 


Gold  and  Palladium. — Palladium  is  as  yet  a  comparatively  rare 
metal.  It  has  been  used  to  some  extent  in  the  industries  and  arts, 
but  practically  to  no  extent  in  dental  golds.  Palladium  is  a  metal 
very  similar  to  platinum  except  for  its  specific  gravity,  11.4,  which 

Fig.  650. — Melting  Points  op  Alloys  of  Gold  and  Palladium. 
2500 


2450 


2400 


2350 


2300 


2250 


2200 


2130 


2100 


2030 


2000 


1950 


1900 


/ 

/ 

/ 

/ 

/ 
/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

10  ;30  30  40  50 

Percentage  of  Palladium. 


60 


5  per  cent.  Pd,  melting  point  2060°  F.,  1127°  C. 
10  "        Pd,         "  "      2145°  F.,  1174°  C. 

15  "        Pd,         "  "      2250°  F.,  1232°  C. 

20  "        Pd,         "  "      2.340°  F.,  1282°  C. 


is  considerably  lower  than  platinum,  and  its  melting  point,  which 
is  also  considerably  lower  than  that  of  platinum. 

It  has  been  stated  that  palladium  makes  gold  brittle.     This  is 
contrary  to  the  author's  findings.   More  than  twenty-five  difl^'erent 


BINARY  ALLOYS  307 

alloys  were  made  containing  from  1  to  30  per  cent,  palladium. 
All  of  them  appeared  quite  uniform  and  remarkably  malleable, 
ductile  and  tenacious. 

Palladium  also  forms  excellent  uniform  alloys  with  copper, 
silver,  etc.,  and  it  is  a  very  valuable  adjunct  to  platinum  in  complex 
gold  alloys.  Its  use,  however,  is  limited,  on  account  of  the  fact 
that  it  exerts  a  strong  decolorizing  action  upon  gold,  3  to  5  per  cent, 
turning  gold  sensibly  lighter,  and  15  to  20  per  cent,  almost  white 
(platinum  color). 

Fig.  (ioO  illustrates  the  melting  point  curve  of  gold-palladium 
alloys. 

Another  remarkable  and  most  valuable  property  that  palladium 
possesses,  is  the  fact  that  although  the  melting  point,  2820°  F. 
(1550°  C),  is  considerably  lower  than  that  of  platinum,  a  given  per- 
centage of  palladium  (by  weight)  will  increase  the  melting  point 
of  gold  more  than  an  equal  amount  of  platinum,  and  in  view  of  the 
fact  that  platinum  in  considerable  percentages  does  not  alloy 
uniformly  with  gold,  it  is  well  to  use  palladium,  as  it  alloys  uni- 
formly with  gold  in  all  proportions.  Therefore  in  alloys  where 
color  is  no  object  palladium  may  be  incorporated  to  very  great 
advantage. 


368  DENTAL  METALLURGY 

TABLE   II.— MELTING   POINTS    OF   BINARY  ALLOYS. 

GOLD— SILVER. 

Melting  point  of  gold 1945°  F.,  1063°  C. 

silver 1761°  F.,    960°  C. 

gold,     95  per  cent.,  silver,    5  per  cent.      .  1945°  F.,  1063°  C. 

gold,     90          "         silver,  10         "  1945°  F.,  1063°  C. 

gold,     85          "          silver,  15          "             .       .  1943°  F.,  1062°  C. 

gold,     70          "          silver,  30          "             .       .  1942°  F.,  1061°  C. 


GOLD— COPPER. 

Melting  point  of  gold 1945°  F.,  1063°  C. 

'      ■     "           copper •.  1980°  F.,  1083°  C. 

gold,     95  per  cent.,  copper,    5  per  cent.    .  .  1840°  F.,  1004°  C. 

gold,     90          "          copper,  10          "          .  .  1735°  F.,    946°  C. 

gold,     85          "          copper,  15          "          .  .  1690°  F.,    921°  C. 

"     .      gold,     82          "         copper,  18         "          .  .  1661°  F.,    905°  C. 


GOLD— PLATINUM. 

Melting  point  of  gold 

"  "  platinum    . 

"  "  gold,     95  per  cent.,  platinum,    5  per  cent. 

"  "  gold,     90  "  platinum,  10  " 

"  "  gold,     85  "  platinum,  15  " 

"  "  gold,     80  "         platinum,  20         " 


1945°  F. 

1063°  C 

3190°  F. 

1755°  C 

2015°  F. 

1102°  C 

2085°  F. 

1141°  C 

2165°  F. 

1165°  C 

2260°  F. 

1228°  C 

Me 


GOLD— PALLADIUM. 

ting  point  of  gold 

"  palladiuin 

"  gold,     95  per  cent.,  palladium,    5  per  cent. 

gold,     90  "  palladium,  10 

■ "  gold,     85  "  palladium,  15  " 

gold,     80  "  palladium,  20 


1945°  F. 

1063°  C 

2820°  F. 

1550°  C 

2060°  F. 

1127°  C 

2145°  F. 

1174°  C 

2250°  F. 

1232°  C 

2340°  F. 

1282°  C 

BINARY  ALLOYS  'MJ 

Gold  and  Metals  in  Group  2. — Iridium. — Iridio- platinum  is 
usually  employed  in  place  of  pure  platinum  on  account  of  its  greater 
hardness  and  durability.  When  experimenting  with  the  series  of 
binary  alloys  previously  discussed,  it  naturally  suggested  itself 
to  the  author,  that  gold  alloyed  with  iridio-i)latiiuim,  instead  of 
pure  platinum,  would  prove  superior.  A  number  of  alloys  were 
attempted  and  the  results  obtained  were  found  invariably  inferior 
to  alloys  of  gold  and  pure  platinum.  The  unsatisfactory  results 
should  have  been  anticipated  because  it  is  well  known  that  iridium 
will  not  alloy  with  gold  uniformly,  but  segregates  on  account  of 
its  extremeh-  high  melting  point  and  high  specific  gravity.  It  is 
quite  certain  that  in  attempting  to  make  the  alloy,  the  following 
occurred:  When  the  iridio-platinum  was  brought  into  the  gold, 
the  heat  used  was  sufficient  to  melt  the  platinum  and  set  free  the 
particles  of  iridium  which  did  not  go  into  solution  with  the  gold 
platinum  mixture,  but  suspended,  and  then  segregated  practically 
in  the  same  way  as  if  free  iridium  were  added  to  gold  without 
the  presence  of  the  platinum. 

The  experimental  alloys  were  made  of  pure  gold  and  15  per  cent, 
iridio-platinum,  and  compared  with  alloys  made  of  pure  gold  and 
15  per  cent,  platinum.  On  rolling  both  to  equal  gauge,  polishing 
and  etching,  the  gold-platinum  alloy  was  found  quite  uniform, 
whereas  some  sections  of  the  gold  iridio-platinum  alloy  were  harder 
and  higher  fusing,  while  other  sections  were  softer  and  lower  fusing 
than  the  gold-platinum  alloy.  In  addition,  all  the  gold-platinum- 
iridium  mixtures  appeared  streaky  and  ununiform,  even  to  the 
naked  eye,  while  the  gold-platin\nn  alloys  appeared  almost  perfect 
even  under  the  microscope. 

Numerous  other  experiments  were  made,  along  these  lines,  and 
in  spite  of  the  fact  that  some  have  advocated  the  use  of  iridio- 
platinum  instead  of  pure  platinum  in  alloys,  it  is  the  author's  con- 
clusion that  pure  platinum  is  far  superior  to  iridio-platinum  as  an 
alloying  element  with  gold. 

Osmium. — No  attempts  have  yet  been  made  to  foi-ni  alloys  with 
osmium,  as  it  is  even  higher  fusing  than  iridium  and  therefore  poor 
results  may  Ix-  anticipated.  The  author  expects,  however,  to 
experiment  with  osmium  shortly,  to  determine  if  there  is  any 
possible  benefit  to  be  derived  from  it,  because  alloys  of  Os  Vt 
are  claimed  to  be  superior  to  alloys  of  Ir   l*t.' 

'   !•■.  ZimiinTiiiaii,  All'iv  ot   I'hilinimi  :iii(l  O.siiiiuiii.  I'.S.   I'.ilml    No.   lO.').'),   11!). 
24 


370  DENTAL   METALLURGY 

Rhodium. — Rhodium  is  another  metal  of  the  platinumi  group  that 
will  prove  of  considerable  benefit  if  sufficient  of  it  could  be  obtained 
at  a  moderate  cost.  It  is  quite  similar  to  palladium.  It  also  has  a 
low  specific  gravity,  12.1,  and  is  considerably  higher  fusing  than 
platinum  (according  to  U.  S.  Bureau  of  Standards), 

The  author  has  not  experimented  with  il  in  the  pure  state,  but 
procured  a  quantity  of  it  in  the  form  of  platinum  containing  10 
per  cent,  rhodium.  This  platinum-rhodium  alio}'  was  used  for  a 
considerable  time  instead  of  pure  platinum.  The  alloys  were  quite 
satisfactory,  but  the  advantages  over  pure  platinum  as  an  alloying' 
agent  are  so  slight,  and  the  cost  so  high,  that  it  appeared  advisable 
to  discontinue  its  use  at  the  time. 

Gold  and  Metals  in  Group  3. — (See  under  Gold  Solders.)    • 

Gold  and  Metals  in  Group  4. — Sometime  after  the  introduction 
of  the  casting  process,  it  became  apparent  that  in  order  to  utilize 
the  casting  process  to  advantage,  alloys  other  than  ordinarily 
obtainable  would  have  to  be  made  in  order  to  insure  satisfactory 
results.  The  ordinary  plate  golds  obtainable,  when  cast  in  small 
bulk,  were  too  soft  and  frail,  and  the  sections  had  to  be  cast  larger 
and  heavier  than  normal,  and  were  therefore  objectionable. 

A  number  of  experiments  were  made  in  attempting  to  cast  the 
various  clasp  metals,  and  the  results  obtained  were  very  unsatis- 
factory. At  this  time  began  to  appear  literature  regarding  indus- 
trial alloys  both  ferrous  and  non-ferrous,  with  the  so-called  rare, 
or  little  known,  metals,  such  as  nickel,  cobalt,  manganese,  tungsten, 
vanadium,  etc.,  enumerated  in  the  table  of  elements  under  Group  4. 

Some  remarkable  results  were  obtained  in  various  industrial 
steels,  brasses,  and  bronzes,  and  it  was  not  unreasonable  to  expect 
that  some  of  these  rare  metals  could  be  utilized  to  advantage  in  the 
formation  of  gold  alloys  for  casting  purposes. 

In  view  of  the  fact  that  there  was  no  precedent  to  follow  and  no 
literature  obtainable  on  the  relation  of  these  metals  to  gold,  it  can 
readily  be  understood  that  the  author's  attempts  to  alloy  these 
rare  metals  with  gold  were  more  or  less  empirical,  and  the  results 
obtained  w^re  no  better  than  should  have  been  anticipated.  Meet- 
ing with  such  poor  success,  the  author  proceeded  with  the  series 
of  researches  into  both  the  binary  and  complex  alloys  of  gold  with 
the  elements  in  groups  one,  two  and  three  and  the  resultant  for- 
mulae developed  are  given  herein  in  the  following  pages. 

Since  then,  a  number  of  experiments  have  been  made  by  other 
investigators,  in  attempting  to  utilize  some  of  the  rare  metals  such 


A   NEW   SKRIES  OF  ALLOWS 


•1 


as  nickel,  tungsten,  molybdenum,  titanium,  etc.,  as  substitutes  for 
iridio-platimmi.    Tlie  results  so  far  lia\e  not  i)roved  successful. 

This  non-success  will  not  appear  strange  to  those  familiar  with 
both  the  chemical  and  physical  characteristics  of  the  elements 
mentioned.  Unless  some  radical  method  of  handling  these  metals 
IS  evolved  iridio-platinum  will  contimie  to  retain  the  position  it 
occupies  (.see  elastic  gold  under  clasp  metals). 

The  author  has  not  by  any  means  given  ny  hope  of  the  possible 
utilization  of  some  of  the  rare  elements  in  eonneetion  with  alloys  for 
casting.  He  is  now  engaged  in  a  series  of  experiments  which  have 
already  shown  promising  results  and  he  hopes  to  have  data  of 
importance  available  for  publication  in  the  near  future. 


A    NEW    SERIES    OF    ALLOYS. 

From  the  preceding  data  on  the  i)roj)erties  of  the  binary  alloys 
of  gold  with  the  metals  in  (Iroup  1,  certain  conclusions  may  be 
drawn  and  data  obtained,  and  it  then  becomes  a  comparatively 
simple  matter  to  form  complex  alloys  for  our  requirements.  Before 
proceeding  to  formulate  a  comi)lex  alloy,  it  will  be  well  to  consider 
again  the  hardness  conferred  upon  gold  by  the  metals  in  (Jroup  1. 


Ji 


/00%  Au 


AuJff 


90ZA>j  -/07oAff 


Au-Fd 


00%Au-/OZ/M 


Au-jft 


9oroAu-/07.re 


Au-Cu 


^OZ  A,, 


Fic;.  fi,51. — CoiMpMi-.-ifivc  h:irfliiOF8  of  liiuMr.s  :ill.,ss. 


As  Will  be  s<-cn  from  j-'ig.  (mI,  pure  silver  lias  piaetieally  no  elleet 
on  gold  as  far  as  increasing  its  liardiiess.  Palladium  has  soiii(> 
hardening  properties,  and  it   is  well  to  be;ir  (!,;,»  in  mind  when  h.r- 


372  DENTAL  METALLURGY 

mulating  an  alloy.  Platinum  has  considerably  more  hardening 
power  than  palladium  and  is  a  factor,  but  copper  is  the  most 
valuable  agent  of  them  all,  and  in  proceeding  to  formulate  the  com- 
plex alloys,  we  must  consider  the  copper  as  the  principal  hardening 
agent  and  the  others  as  adjuncts. 

Gold  for  Crown,  Bridge  and  Plate  Work.— Gold  Plate  No.  1.— 
Bearing  in  mind  the  hardening  power,  and  the  effect  on  melting 
point  produced  by  the  alloying  elements,  let  us  consider  such  a 
formula  as  the  following: 

FORMULA   OF   GOLD   PLATE   No.    1. 

Per  cent. 

Gold .  88.0 

Platinum .  7.5 

Palladium 2.5 

Silver ! 2.0 

Total 100.0 

Melting  Point  2075°  F.,  1135°  C. 

This  alloy  is  equivalent  in  hardness  to  ordinary  22-K.  gold, 
containing  91.6  per  cent,  gold,  3.5  to  4  per  cent,  copper  and  4.5 
to  5  per  cent,  silver.  Now,  as  the  copper  is  the  active  hardening 
agent  in  the  22-K.  gold  and  as  we  know  from  the  preceding  data 
that  platinum  and  palladium  exert  somewhat  less  than  half  of  the 
hardening  influence  of  copper,  it  will  be  seen  that  the  total  of  10 
parts  platinum  and  palladium  are  about  equal  in  hardening  power 
to  the  3.5  to  4  parts  of  copper  usually  present  in  22-K.  gold;  and  thus 
we  get  an  alloy  equivalent  in  hardness  to  the  ordinary  22-K.  plate. 

The  silver  content,  2  parts,  is  no  factor  whatever,  except  as  a 
color-modifying  agent,  because  it  is  an  object  to  adhere  to  a  certain 
standard  of  color  throughout  the  whole  series  of  alloys.  As  there 
is  no  copper  whatever  present  in  this  alloy,  it  is  absolutely  non- 
oxidizable,  but  the  great  advantage  that  an  alloy  of  this  character 
possesses  over  an  ordinary  22-K.  plate  is  the  fact  that  its  melting 
point  is  much  above  that  of  ordinary  22-K.  gold,  approximately 
225°  F  to  250°  F.  higher,  and  instead  of  sweating  a  band  and  floor, 
it  may  be  very  easily  soldered  with  pure  gold  or  22-K.  plate  and 
resoldered  with  the  same  or  lower-grade  plate  gold  innumerable 
times,  without  any  danger  of  burning  or  blistering. 

Any,  or  all,  of  the  alloys  in  the  series  following  plate  No.  2,  may 
be  safely  used  as  solders  on  plate  No.  1,  thus  permitting  many  sol- 
dering operations  without  danger  of  burning  the  gold,  as  may  occur 
in  sweating,  or  the  danger  of  the  solder  (if  poor  quality)  burning 


A  NEW  SERIES  OF  ALLOYS  373 

iuti)  and  alloyiiiii  witli  tlu'  ^old,  as  often  occurs  when  iisin*;'  the 
so-called  " easy-fiowiug"  solders.  It  is  t>\ident,  therefore,  that 
this  alloy  oii'ers  a  fjreat  many  advantajies  o\er  the  ordinary  22-K. 
plate  jiold. 

Gold  Plate  No.  2. — As  has  been  impressed  by  Dr.  Peeso,  it  is 
al)solutely  essential  to  use  for  removable  bridge-work,  a  hard, 
durable  gold,  such  as  U.  S.  coin  gold.  It  may  be  well,  at  this  time, 
to  state  that  U.  S.  coin  gold  contains  90  per  cent,  pure  gold  and  10 
per  cent,  copper,  whereas  the  so-called  coin  gold  obtainable  from 
most  supply  houses  contains,  as  a  rule,  some  silver,  which  softens 
it  and  makes  it  work  more  easily,  it  therefore  does  not  possess  the 
strength  and  durability  required. 

The  following  formula  replaces  coin  gold  most  satisfactorily: 

FORMULA    OF  GOLD   PLATE   No.   2. 

Per  cent. 

Gold 84.5 

Platinum 8.. 5 

Palladium 2.0 

Silver 0.5 

Copper 4.5 

Total 100.0 

Melting  Point  1975°  F.,  1080°  C. 

In  this  formula,  in  order  to  obtain  the  equivalent  hardness  of 
coin  gold,  it  is  necessary  to  use  copper.  We  can  again  readily  see 
just  how  the  hardening  properties  of  the  alloying  elements  are 
utilized.  We  have  4.5  per  cent,  copper,  and  the  platinum  and 
palladium  replace  the  rest  of  the  copper,  thus  giving  us  an  alloy 
equal  to  V.  S.  coin  gold.  This  oxidizes,  of  course,  to  a  slight  extent, 
but  the  oxidation  is  not  objectionable,  and  this  alloy  can  be  used 
to  replace  coin  gold  i)ractically  for  every  purpose,  and  may  be 
.soldered  with  other  alloys  in  the  series  which  have  the  same  color. 
When  soldered  with  casting  gold,  B  or  (",  the  attachment  of  the 
floor  to  a  })and  cannot  open  up  during  the  final  soldering  unless 
fleliberately  abused,  because  the  soldered  junctions  are  actually 
higher  in  melting  point  than  ordinary  gold  plate. 

The  fusing  point  of  this  alloy  is  approximately  225°  F.  higher 
than  coin  gold,  an<l  it  possesses  all  the  advantages  over  coin  that 
the  No.  1  formula  has  over  22-K.  gold, 

'i'hesc  allo\'s,  Xos.  I  and  2,  can  be  utilized  to  great  advantage 
in  the  con.struction  of  swaged  plates,  both  full  and  |)artial,  especially 
where  it  is  desired  to  make  the  |)lates  (»f  two  or  three  thin  hiNcrs, 
(Ml  account  r)f  the  high  melting  |)oint  (»f  the  alloys,  which  permits 


874  DENTAL  METALLUBGY 

of  thorough  soldering  of  the  lamina?  without  danger  of  burning. 
When  used  in  conjunction  with  the  other  alloys  in  the  series,  these 
golds  enable  the  operator  to  produce  dentures  far  superior  to  those 
made  from  the  golds  ordinarily  employed,  on  account  of  increased 
strength,  minimized  bulk,  and  perfect  color  harmony,  throughout 
the  whole  structure. 

It  should  be  borne  in  mind  that  high  fusing  golds,  such  as  these, 
cannot  be  "sweated"  advantageously.  This  is  a  characteristic  of 
all  gold  alloys  high  in  platinum  metals. 

Alloys  for  Prosthetic  Castings. — As  has  been  previously  stated,  in 
order  to  cast  sections  of  bridge-work,  saddles,  partial  plates,  etc.,  it 
is  essential  to  have  alloys  that  are  rigid  in  the  cast  form,  to  obviate 
the  necessity  for  increased  bulk.  Again,  the  value  of  the  hardening 
properties  of  the  alloying  elements  becomes  apparent,  as  in  the 
following : 

FORMULA    OF    CASTING    GOLD    "B." 

Per  cent. 

Gold 80.0 

Platinum 9.5 

Palladium 2.5 

Silver 1.0 

Copper 7.0 

Total  .      .      100.0 

Melti?jg  Poin-t  1975°  F.,  1080°  C. 

We  have  here  7  per  cent,  copper  and  a  total  of  12  per  cent,  of 
the  platinum  metals,  which  makes  an  alloy  considerably  harder 
than  coin  gold.  When  cast,  this  alloy  is  about  midway  in  hardness 
between  rolled  coin  gold  and  clasp  metal.  The  melting  point  of 
this  alloy  is  about  50°  F.  below  pure  gold.  It  is  intended  for  use 
with  the  nitrous  oxide  blow-pipe  and  should  be  melted  with  same, 
if  a  considerable  quantity  of  gold  is  to  be  cast.  Sufficient  quantities 
for  small  castings  can  be  melted  with  the  ordinary  blow-pipe. 
The  copper  content  being  comparatively  low  permits  of  the  use 
of  the  nitrous-oxide  blow-pipe  without  any  material  change  or 
deterioration  of  the  alloy,  if  a  suitable  reducing  flux  is  used  in 
connection  with  it. 

This  alloy  corresponds  in  color  with  plate  No.  1  or  No.  2,  and  may 
be  used  to  cast  cusps  or  cusps  and  contours  directly  to  bands  of 
either  plate  No.  1  or  plate  No.  2.  It  makes  a  particularly  suitable 
gold  for  cast  occlusal  surfaces  on  account  of  its  hardness  and  dur- 
ability. 

The  next  formula  is  a  modification  of  "B"  and  brings  out  an 


A  NEW  SERIES  oP  ALLOYS  37o 

interesting  point  in  connection  with  the  effect  of  copper  and  the 
phitiiunn  metals  on  the  decrease  and  increase  of  melting  points. 

FORMULA   OF  CASTING   GOLD   "C." 

Per  cent. 

Gold 80.5 

Platinum q  5 

Palladium 2.0 

Silver 2.0 

Gopper •.      .      .  9.0 

Total  .       .      100. 1) 

Meltin-j;  Point  1S00°  F.,  980°  C. 

We  note  in  this  formula  an  increase  of  two  parts  of  copper 
and  a  decrease  of  a  total  of  3.5  parts  platinum  and  palladium, 
the  consequence  being  that  the  melting  point  is  dropped  by  the 
increase  of  copper  and  by  the  decrease  of  the  platinum  metals. 
The  melting  point  is  dropped  about  100°  F.  and  brought  down  to 
approximately  that  of  22-K.  gold.  This  lowering  of  the  melting 
point  permits  this  alloy  to  be  melted  readily  for  large  or  small  casting 
with  an  efficient  illuminating  gas  and  air  blow-pipe.  It  is  identical 
in  strength,  hardness,  color,  etc.,  with  casting  gold  "B"  except  the 
fusing  point  and  resistance  to  the  nitrous  oxide  blow-pipe  flame. 
If  the  latter  is  used,  caution  must  be  taken  to  use  a  reducing  flux 
and  not  superheat  the  metal.  This  applies  to  coin  gold,  too,  if 
same  is  cast.  Excessive  heat,  if  aijplied  with  the  nitrous^  oxide 
blow-pipe,  atid  lack  of  a  suitable  redttciiu/  flux,  icill  permit  the 
oxidation  of  considerable  copper  and  the  dissemination  of  oxide 
throughout  the  casting. 

Gold  for  Inlay  Casting. — Since  the  introduction  of  the  casting 
process,  pure  gold  has  l)een  generally  advocated  for  cast  fillings, 
etc.,  on  account  of  its  suppo.sed  minimum  shrinkage,  softness  and 
malleability,  and  consequent  ease  with  which  the  margins  could 
be  burnished  to  eliminate  the  cement  line  of  an  inlay. 

-V  good  many  operators  have  failed  to  cast  pure  gold  satis- 
factorily and  claim  that  they  can  cast  inlays  with  scrap  gold  and 
produce  better  and  sharper  margins.  To  those  who  have  not 
experienced  this  difficulty,  it  may  appear  very  strange,  but,  never- 
theless, it  is  a  fact  that  alloyed  gold,  when  ])r()perly  alloyed,  and 
under  fair-casting  conditions,  invariably  casts  with  sharp,  true 
margins,  whereas  pure  gold  has  very  often  failed  to  accomplish  the 
|)ur|)ose,  both  at  the  hands  of  the  author  and  many  others. 

It  may  lie  well  to  consider  that  the  casting  of  scrap  gold  of  indcfi- 


376  DENTAL  METALLURGY 

nite  composition  is  rather  a  hazardous  and  usually  unsatisfactory 
procedure  and  a  great  many  operators  recognizing  that  fact,  are 
using  22-K.  gold,  coin  gold,  etc.,  with  better  results  than  they 
have  been  able  to  obtain  with  pure  gold. 

It  is  a  well-known  fact  that  pure  platinum,  pure  palladium  and 
pure  silver  absorb  hydrogen,  oxygen  and  other  gases,  while  in  the 
molten  state,  and  retain  some  of  the  gases  upon  solidification.  It 
is  not  generally  known,  but  nevertheless  true,  that  pure  gold  absorbs 
nitrogen,  hydrogen  and  oxygen,  and  retains  a  considerable  per- 
centage of  one  or  more  of  the  absorbed  gases  upon  solidification.^ 
This  tendency,  on  the  part  of  the  metals  mentioned,  to  absorb 
gases,  is  minimized  and  sometimes  entirely  eliminated  by  alloying 
and  a  small  percentage  of  copper,  palladium  or  platinum  will  mater- 
ially alter  the  behavior  of  pure  gold  upon  solidification.  Castings 
made  with  a  slightly-alloyed,  pure  gold,  will  be  found  to  possess 
sharp  margins  and  practically  equal  pure  gold  in  color,  ductility,  and 
facility  of  burnishing,  and  to  be  comparatively  free  from  cavities 
or  blow-holes,  such  as  are  often  found  in  unalloyed  gold  castings. 

A  number  of  cases  under  observation  have  shown  that  fillings 
of  slightly-alloyed  gold  do  not,  after  a  period  of  wear,  present  the 
same  pitted  surface  so  characteristic  of  cast  pure  gold  fillings 
under  the  same  conditions. 

The  rounding  of  the  margins  in  cast  pure  gold  fillings  is  usually 
accompanied  by  a  separation  of  the  residue  button  from  the  casting 
which  takes  place  just  prior  to  the  completion  of  solidification.  This 
occurs  particularly  when  a  comparatively  large  sprue  is  used,  and 
more  especially  when  a  large  residue  button  is  used  at  the  same 
time.  An  explanation  of  this  occurrence  may  reasonably  be 
attributed  to  the  following:  If  the  sprue  is  quite  large,  and  the  gold 
residue  button  large,  the  residue  remains  fluid  for  a  considerable 
period  of  time  after  the  casting  pressure  has  been  applied,  and  there 
appears  to  be  a  tendency  for  the  large  button  to  draw  to  it  the  gold 
of  the  casting  through  the  medium  of  the  large  gate  (the  sprue). 
A  large  button  of  gold  very  often  draws  only  part  of  the  sprue  to 
it,  thus  separating  the  connection  between  the  residue  button 
and  the  casting,  and  arresting  the  exercise  of  the  casting  pressure 
which  would  otherwise  be  transmitted  from  the  button  to  the 
sprue  and  then  to  the  casting  proper.  For  those  who  wish  to  use 
pure  gold  for  casting,  it  is  suggested  that  the  quantity  of  gold  used 

1  Roberts- Austen,  Introduction  to  the  Study  of  Metallurgy. 


A  NEW  SERIES  OF  ALLOYS  377 

in  the  casting  operation  should  not  exceed  more  than  three  pi-nny- 
weights  above  the  amount  actually  required  for  the  casting  proi)er, 
and  also  that  the  sprue  l)e  no  larger  than  1()  gauge  B.  and  S.  This 
will  serve  to  lessen  the  area  of  connection  between  the  casting  and 
residue  button,  so  that  this  area  (the  sprue)  may  solidify  more 
rapidly,  and  in  conjunction  with  the  smaller  button,  which  naturally 
freezes  more  rapidly,  tend  to  prevent  the  separation  pre^-iously 
discussed. 

Another  point  that  is  well  to  consider,  is  the  fact  that  alloying 
of  gold  reduces  the  surface  tension  and  cohesion  of  the  molecules 
while  in  a  molten  state,  and  increases  the  fluidity,  thus  facilitating 
the  flow  of  the  metal,  requiring  less  pressure  to  force  the  gold  into 
the  mould,  and  consequently,  lessening  the  danger  of  distorting  the 
mmild.    (See  investment  compounds  for  casting.) 

FORMULA  OF  CASTINCi   GOLD   "A." 

Per  cent. 

Gold 97.0 

Platinum 1 .  .'> 

Palladium 0.;5 

Silver 0..i 

Copper 0.9 

Total 100.0 

Meltin-g  Point  194.5°  F.,  106.3°  C. 

This  alloy  makes  an  efficient  substitute  for  pure  gold,  as  the 
comparatively  small  amount  of  alloy  does  not  harden  the  gold 
sufficiently  to  prevent  burnishing,  nor  does  it  affect  the  color 
perceptibly.  Copper  is  the  most  suitable  agent  for  increasing  the 
fluidity,  and  the  small  percentage  used  does  not  materially  harden 
the  gold.  The  drop  in  melting  point  is  compensated  for  by  the 
platinum,  and  the  small  percentage  of  silver  counteracts  the  color- 
ing effect  of  the  copper  on  the  gold,  the  consequent  alloy  possessing 
practically  the  same  melting  point  as  pure  gold,  and  producing, 
almost  invariably,  sound  castings,  withont  the  special  precaution 
which  must  be  taken  when  pure  gold  is  used. 

This  alloy  will  be  found  suitable  for  use  in  teeth  close  to  others, 
with  fillings  or  inlays  made  of  pure  gold,  in  order  to  maintain  color 
harmony. 

As  all  the  alloys  in  the  series,  excepting  the  casting  gold  A  and 
the  elastic  alloy  described  later,  are  practically  of  a  uniform  colorand 
somewhat  lighter  (grayish  red)  and  less  cons|)i('uo\is  than  pure  gold 
or  coin  gold,  it  has  been  found  advisable  to  also  formulate  an  alloy 
for  casting  inlays  to  harinoni'/e  in  color  with  the  rest  of  th<-  series. 


S?8  DENTAL  METALLURGY 

FORMULA   FOR   CASTING   GOLD   "D." 

Per  cent 

Gold    .    ■ '....'..        95.0 

Palladium 3.3 

Silver 0.4 

Copper 1.3 

Total 100.0 

Melting  Point  1945°  F.,  1063°  C. 

In  this  alloy,  the  palladium  decolorizes  the  pure  gold,  and  raises 
the  melting  point.  The  copper  brings  it  back  to  the  pure  gold 
standard,  and  by  the  addition  of  the  small  percentage  of  silver  to 
counteract  the  reddening  effect  of  the  copper,  a  color  effect  is 
obtained  in  perfect  harmony  with  the  rest  of  the  series. 

This  gold  is  quite  soft  and  malleable  and  may  be  burnished  with 
practically  the  same  facility  as  pure  gold.  This  question  of  bur- 
nishing margins  of  inlays  is  rather  a  more  or  less  indefinite  procedure. 
It  is  the  author's  opinion  that  very  little  effective  burnishing 
(spinning)  can  be  done  on  inlay  margins,  and  that  only  after  the 
margins  are  stoned  down  to  an  extremely  thin  edge.  Experience 
has  shown  that  it  is  advisable  to  use  hard  and  durable  alloys  for 
inlays,  especially  those  intended  to  aid  in  supporting  bridge-work, 
and  then  only  when  supplemented  with  posts  or  dowels. 

This  alloy,  D,  can  be  combined  with  B  or  C,  to  obtain  harder 
alloys,  with  no  difficulty  and  no  change  in  color,  thus  enabling  the 
operator  to  obtain  practically  any  degree  of  hardness  for  special 
requirements  in  inlay  casting. 

CLASP   METALS. 

As  previously  stated,  the  alloys  known  as  clasp  metal,  or  plat- 
inized gold,  as  ordinarily  obtainable,  have  been  used,  with  poor 
results,  for  casting  sections  of  bridge-work,  etc.,  and  are  being 
used  to  a  large  extent,  and  with  but  mediocre  results,  as  a  substi- 
tute for  iridio-platinum  for  crown  posts,  dowels,  etc.  The  ordinary 
clasp  metal  is  also  used  to  a  considerable  extent  for  posts  or  dowels 
in  the  construction  of  cast  base  crowns,  with  usually  poor  results, 
on  account  of  its  brittleness,  especially  after  it  has  been  cast 
against.  There  appear  to  be  about  four  distinct  types  of  clasp 
metal  obtainable  at  the  supply  houses. 

The  following  formulae  are  nearly  exact  and  type  one  and  two 
readily  indicate  the  particular  role  that  copper  plays  as  a  hardening 
agent : 


CLASP  METALS  I'.TO 

TABLE    III.— COMPOSITION    OF   CLASP    METALS. 


CoNSTiTUKNT  Metals.  Type].*  Type  2.*  Type  3.*  Type  4.**  '  Elastic  gold. 

Gold 63  65  63  6.5  64.0 

Siilver 1-t  15  17  6  1.5 

Copper       ....  21  13  7  7  7.0 

Platinum    ....  2  7  13  18  11.0 

Palladium        ...  4  16.5 


Comparative  1600°  F.       1725°  F.       1S60°  F.       1960°  F.       2100°  F. 

Melting  Point  870°  C.         940°  C.       1015°  C.       1070°  C.        lI.-)0°  C. 


*  From  analysi.-;.     **  Is  known  commercially  a.s  "high  fusing"  clasp  metal. 

Type  1  represents  a  class  of  clasp  metals  of  which  there  are 
several  on  the  market.  They  contain  a  trace  of  platinum,  so  that 
they  may  legally  he  called  platinized  gold,  and  a  very  high  per- 
centage of  copper.  The  copper  content  confers  a  high  degree  of 
hardness  and  elasticity  upon  the  alloy,  but  during  subsequent 
heating  (soldering  and  annealing)  and  working,  the  alloy  softens 
considerably  and  loses  a  good  deal  of  the  original  elasticity,  and 
sometimes  becomes  very  brittle,  especially  when  over-heated.^ 
As  the  melting  point  is  quite  low,  soldering  with  even  a  compara- 
tively low  fusing  solder  is  apt  to  endanger  the  integrity  of  the 
alloy  more  often  than  not. 

Type  2  represents  a  class  of  clasp  metals  which  contain  a  larger 
percentage  of  platinum  and  less  copper.  This  alloy,  while  not  quite 
as  elastic  before  annealing,  retains  its  elasticity  after  annealing  or 
soldering,  better  than  type  one,  and  makes  a  quite  satisfactory 
material  for  clasps  for  vulcanite  work,  etc.,  if  not  excessively  heated 
and  otherwise  abused. 

Neither  of  the  two  alloys  are  suitable  for  work  recjuiring  repeated 
.soldering  operations.  Posts  or  dowels  made  of  these  alloys  and 
ca.st  again.st,  usually  .show  a  partial  fusion  and  although  this  fusion 
is  not  always  evident,  the  i)osts  if  cast  against  break  away  (at  the 
junction)  ultimately.  These  alloys  are  ab.sohitely  unfit  for  the 
making  of  split  jiins. 

'JVpe  '.]  ofl'ers  a  nnich  better  material.  It  contains  still  less 
copper,  and  more  platinum,  but  has  not  sufficient  strength  and  elas- 
ticity.    For  want  of  a  better  material,   it   has  been   used   for  the 

•  CJold-«ilver-coi)per  alloy.s  containing  over  15  per  ((^nl.  foppifr  an;  <|iiilc  luillie, 
very  unnnirorrn,  and  variahjc  in  licli.-tvior  upon  nitittr.iWue,. 


380      ■  DENTAL  METALLURGY 

construction  of  split  pins  for  a  number  of  years.  In  addition,  the 
fusing  point,  although  higher  than  that  of  types  one  and  two,  is  too 
low,  and  when  attempting  to  solder  the  solid  portion  of  a  split  pin 
with  coin  gold,  the  metal  is  apt  to  fuse  partly,  becoming  granular 
and  brittle,  and  the  finished  pin  is  apt  to  give  out  in  use.  The  type 
three  clasp  metal  has  been  cast  against  with  fair  results,  but  the 
danger  of  burning  it  is  imminent. 

In  the  three  types  of  clasp  metals  under  discussion  is  demon- 
strated the  value  of  copper,  and  its  superiority  over  platinum  as  a 
hardening  agent,  and  the  value  of  platinum,  in  raising  the  melting 
point  lowered  by  the  copper. 

A  number  of  experiments  were  made  to  improve  the  type  three 
clasp  metal,  and  it  can  readily  be  seen  from  formula  of  type  four, 
how  comparatively  simple  it  was  to  do  so,  having  established  the 
properties  of  the  binary  alloys  as  a  foundation.  By  raising  the 
platinum  to  18  points,  the  melting  point  and  the  elasticity  were 
increased  somewhat.  Even  at  this  stage,  the  advance  in  melting 
point  appeared  insufficient,  and,  as  it  was  deemed  advisable  to  avoid 
more  platinum  on  account  of  the  danger  of  its  not  alloying  uniformly, 
palladium  which  alloys  readily  was  added,  and  the  melting  point 
increased  to  a  total  of  app.  100°  F.  above  type  three.  No  more 
palladium  was  used  on  account  of  its  decolorizing  action.  With 
the  comparatively  small  content  (4  per  cent.),  the  color  of  the 
alloy  is  still  quite  gold-like.  This  alloy  has  been  used  with  uni- 
formly good  results.  It  may  be  soldered  safely  with  coin  gold  (for 
split  pins) ,  and  may  be  cast  against  safely  if  a  comparatively  heavy 
gauge  of  wire  (above  10  g.  B  &  S)  is  used. 

In  view  of  the  fact  that  for  split  pins,  dowels  for  cast  base 
crowns,  etc.,  color  is  no  object,  it  was  deemed  advisable  to  raise  the 
melting  point  even  above  that  of  type  four  and  the  elastic  gold 
was  formulated,  using  a  considerable  percentage  of  palladium. 
The  palladium,  of  course,  decolorized  the  alloy  completely,  but 
raised  the  melting  point  very  considerably,  and,  in  conjunction  with 
the  copper  and  the  considerable  percentage  of  platinum,  produced 
an  elasticity  even  beyond  that  of  type  four,  and  a  melting  point 
very  considerably  higher. 

This  alloy  can  be  soldered  with  perfect  safety  with  pure  gold 
or  anything  below  that  in  melting  point.  It  may  be  cast  against 
with  perfect  safety  (except  very  thin  wire) ,  and  retains  its  strength 
and  elasticity  after  any  reasonable  number  of  soldering  operations 
that  it  may  necessarily  be  subjected  to.     It  may  he  soldered  very 


GOLD  SOLDERS  381 

readili/  and  iclfli  hdtvr  union  than  iridio-platininu.  It  /.v  nincli  more 
rigid  than  ordinary  iridio-platinuin,  and  possesses  elasticiti/  that  is 
practically  absent  in  all  of  the  iridio-platinum  alloys  and  it  may 
therefore  replace  the  latter  and  ordinary  clasp  metal  for  a  great  many 
purposes. 

In  the  makino;  of  split  posts  of  the  elastic  gold,  it  is  advisable  to 
solder  the  area  that  is  intended  should  remain  solid  with  coin  gold, 
as  it  oilers  a  strong  color  contrast  to  the  comparatively  white  elastic 
gold. 

The  line  of  demarkation  between  the  solid  and  the  split  portions 
of  the  post,  will  be  then  readily  distinguished.  As  the  coin  gold  is 
of  sufficiently  high  melting  point,  it  will  not  refllow  during  later  sol- 
dering operations. 

The  comparative  hardness  and  the  elasticity  of  the  four  types  of 
clasp  metals  and  the  "elastic"  gold  is  approximately  as  illustrated 
in  the  following : 

COMPARATIVE   ELASTICITY    AFTER    ROLLING    AND 
ANNEALING    ONCE. 

Type  1.  Type  2.  Type  3.  Type  4.  "  Elastic"  Gold. 

10  9  8  9+  10  + 

COMPARATIVE   LOSS   OF   ELASTICITY  AFTER  SOLDERING   AND 
ANNEALING    THREE    TIMES. 


Type  L 

Type  2. 

Type  S. 

Type  4. 

"Elastic"    Gold. 

2-.3 

1-2 

1  + 

1 

.5-1 

Types  one  and  two  become  very  brittle  if  overheated  during 
soldering.  Type  three  is  subject  to  same  to  a  lesser  degree  and  type 
four  only  occasionally.  The  "elastic"  gold  appears  practically 
immune  to  temperatures  below  the  melting  point  of  pure  gold. 

r|as|)  metal  should  always  be  annealed  before  use,  as  maiuifac- 
turers  often  neglect  to  do  so  after  the  rolling  or  drawing  operations. 

GOLD  SOLDERS. 

In  order  to  obtain  the  (Icsiriibic  \niiformity  of  color  in  a  denture 
without  silbsecpient  gold  "washing,"  Jis  adx'oeated  by  some,  it 
was  necessary  to  formulate  solders  to  correspond  in  color  with  the 
other  alloys.  Incidentallx',  it  is  well  to  consider-  the  imposition  that 
has  been  practiced  n|)on  the  |)rofcssion  by  some  of  the  imscnipnions 
manufacturers  of  gold  solders. 


382  '  DENTAL  METALLURGY 

For  many  years,  a  great  many  in  the  profession  have  been  under 
the  impression  that  gold  solders  stamped  18-K.  were  actually  18-K, 
(75  per  cent,  gold)  in  fineness.  This  was  not  so  and  a  number  of 
the  manufacturers  were  producing,  and  are  still  producing,  solders 
marked  18-K.,  etc.,  anywhere  from  two  to  six  karats  below  the 
mark.  In  addition,  the  solders  mentioned  are  not  only  deficient 
in  gold  content,  but  contain  many  deleterious  alloying  elements, 
such  as  high  percentages  of  cadmium,  iron,  etc.,  in  order  to  complete 
the  required  total  content  of  base  metals  in  the  solders. 

On  the  other  hand,  the  reputable  manufacturers  have  consis- 
tently stated  that  their  solders  were  approximately  two  karats 
below  the  mark,  and  intended  for  use  on  that  karat  of  plate.  The 
reputable  manufacturers  have  recently  started  to  stamp  the  actual 
fineness  on  their  solders  and  the  others  have  followed  suit;  but 
some  manufacturers  still  persist  in  the  practice  of  misrepresentation 
by  not  actually  furnishing  the  gold  content  indicated  by  the  fine- 
ness stamp  on  the  product. 

Alloys  of  Gold  with  Metals  in  Group  3. — Besides  zinc,  the  other 
three  metals  in  Group  3,  namely,  cadmium,  tin  and  aluminum,  are 
being  used  to  a  very  large  extent  as  alloying  elements  in  making 
gold  solders.  Cadmium,  if  used  in  large  percentages,  debases  the 
alloy  very  considerably  and  renders  it  practically  unfit  for  use  in 
the  mouth. 

Tin  is  also  used  to  a  considerable  extent,  as  it  lowers  the  melting 
point  of  gold  very  considerably,  but  it  renders  the  gold  quite 
brittle  and  aids  materially  in  the  tendency  of  solder  to  burn  into 
the  work,  which  property  is  characteristic  of  all  the  so-called  easy 
flowing  solders.  The  term  "easy-flowing"  is  undoubtedly  a  mis- 
nomer. Rather,  these  solders  melt  "easy,"  but  do  not  flow  "easily." 
They  ball  up  and  stick,  and  if  the  heat  is  forced  to  induce  flow,  they 
burn  into  the  work  with  consequences  too  well  known  to  require 
further  discussion. 

The  value  of  aluminum,  as  a  constituent  of  gold  solders,  is  yet 
to  be  proved.  It  is  a  constituent  of  most  of  the  patent  commercial 
alloys  used  by  jewelers  in  compounding  their  solders. 

Solders  made  according  to  the  following  formulae  will  be  found 
satisfactory  in  color,  strength,  and  fusing  point,  although  higher 
in  fusing  point  than  the  so-called  easy-flowing  solders,  for  which 
there  seems  to  be  a  "popular"  demand.  They  will  be  found  to 
flow  readily  if  the  work  on  which  they  are  to  be  used  is  brought  up 
to  the  proper  temperature. 


COMPOVNDIXG  OF  GOLD  ALLOYS  383 

FORMULAS  FOR  GOLD  SOLDERS. 

SOLDER  No.  S4. 

Per  cent. 

Gold 84.0 

Copper 7.5 

Silver 5.5 

Zinc      . 3.0 

M.  P.  lOM"  F.,  000°  C.  (20-Karat  fine). 


SOLDER  Xo.  7(). 

Gold    ...                         70.0 

Copper                        11.5 

Silver 8.5 

Zinc 4.0 

M.  P.  1550°  F.,  840°  C.  (IS-Karat  fine). 


SOLDER  No.  08. 

Gold 68.0 

( 'i  )pper 4.5 

Silver         12.5 

Zinc 5.0 

M.  P.  14.50°  F.,  785°  C.  (16^-Karat  fine). 

Tlie  first  and  second,  (S4  and  7(),  will  be  found  sufficiently  low 
in  incltint;  point  for  all  ordinary  operations  where  Dr.  Peeso  recom- 
mends the  use  of  his  No.  21  and  No.  19  solder.  The  number  (38 
solder,  although  higher  in  actual  gold  content  than  the  best  so-called 
18-K.  solder  obtainable,  is  still  too  low  a  grade  to  be  used  in  general 
work,  especially  in  fixed  l)ridge-work,  but  may  be  used  in  connection 
with  rcmo\able  bridge-work  or  plate  work  because  in  that  work  or 
repah-  work  there  is  rccpiircd  at  times  a  lower-fusing  solder. 

COMPOUNDING    OF    GOLD    ALLOYS. 

Althongh  the  new  series  of  alloys,  made  with  practically  no 
deviation  from  the  formula*  which  are  given  herein,  may  be  ]nir- 
cha.sed  from  the  supply  houses,  the  author  considers  it  well  to  give 
a  mimbcr  of  directions  to  those  who  may  desire  to  compound  the 
various  alloys. 

It  is  not  |)ractical  to  make  a  small  (piantit^',  es|)ccially  if  for  plate 
gold  or  solder  which  is  to  be  poured  into  an  ingot  mould  and  rolled. 
The  higher  the  melting  point  of  the  alloy,  the  more  necessary  it  is 
to  have  a  comparatively  large  (piantity,  an<l  it  is  well  not  to  attempt 
less  than  five  ounces  for  plate  gold  and  three  ounces  for  solder. 
The  ela.sti<'  alloy  should  be  made  in  even  larger  (piantity  as  it  freezes 
very  raj)idly. 


384  DENTAL  METALLURGY 

It  is  practically  impossible  to  alloy  platinum  or  palladium  with 
gold  in  the  small  blast  furnace  which  the  practitioner  is  likely  to 
have  in  his  laboratory.  For  all  alloys  with  platinum  metals  (made 
on  the  small  scale  previously  mentioned)  it  is  well  to  alloy  the 
gold  and  the  platinum  metals  (rolled  very  thin),  first  on  a  charcoal 
block,  using  the  nitrous  oxide  and  illuminating  gas  blow-pipe,  or 
preferably  the  oxygen  and  illuminating  gas  blow-pipe.  A  number 
of  the  alloyed  nuggets  can  then  be  placed  in  a  crucible  on  top  of 
the  required  silver  and  copper  content,  covered  with  a  suitable 
reducing  flux  and  melted,  poured  into  an  ingot  mould  and  rolled 
or  drawn. 

When  copper  is  to  be  used,  it  is  essential  that  same  be  chemically 
pure  and  especial  precaution  must  be  exercised  to  prevent  oxidation 
as  far  as  possible,  which  latter  can  be  accomplished  by  the  use  of 
a  strong  reducing  flux.     (See  under  Fluxes.) 

A  slight  excess  of  copper  should  always  be  added  to  allow  for 
some  loss  which  invariably  occurs. 

If  the  alloy  that  it  is  intended  to  make  is  to  be  used  for  casting 
purposes,  the  procedure  is  the  same  as  previously  described,  except- 
ing that  the  metal,  when  properly  molten,  can  be  poured  into  a 
pail  of  water  and  thus  granulated.  This  procedure  saves  the  labor 
of  rolling  the  ingot  and  the  granulated  form  of  gold  is  as  convenient 
to  use  for  casting  as  any  other. 

In  all  cases,  just  before  pouring  the  contents,  the  crucible  should 
be  well  shaken  to  insure  a  thorough  admixture  of  the  metals. 

Some  writers  advocate  the  preparation  of  alloys  for  casting 
in  the  following  manner:  Melt  the  gold,  feed  the  platinum  (very 
thin)  into  the  molten  gold  and  then  add  copper,  etc.  It  is  impos- 
sible to  make  a  uniform  alloy  in  this  manner,  especially  if  copper  is 
used,  because  a  considerable  amount  of  the  copper  is  oxidized  on 
account  of  direct  contact  with  the  blow-pipe  flame.  In  the  author's 
hands  the  directions  previously  given  have  been  found  to  work  out 
admirably. 

In  compounding  solders  where  zinc  and  copper  are  the  con- 
stituents it  has  been  advocated  that  brass  which  contains  copper 
and  zinc  be  used  in  order  to  prevent  the  loss  of  zinc  through  oxida- 
tion and  volatilization.  This  is  a  very  dangerous  practice,  and 
the  results  are  very  unsatisfactory  because  it  is  impossible  to 
obtain  a  commercial  brass  that  does  not  contain  a  considerable 
percentage  of  lead,  tin,  and  traces  of  antimony,  etc.,  which  are  all 
very  harmful  substances  and  invariably  tend  to  make  the  solder 


REFRACTORY  MATERIALS  ;}85 

brittle.  It  is  therefore  necessary  to  first  make  an  alloy  of  chemi- 
cally jjure  zinc  and  chemically  pure  copper  in  a  proportion  of  say 
one  part  zinc  and  two  parts  copper.  This  alloy,  when  properly 
melted,  is  granulated  by  pouring  into  water,  and  then,  if  carefull\- 
gathered,  dried  and  weighed,  the  loss  of  zinc  can  be  determined. 
The  necessary  additional  copper  to  make  the  required  alloy  is  then 
calculated  and  added  w^hen  compounding  the  solder. 

It  is  well,  of  course,  to  make  a  considerable  quantity  of  the  copper 
zinc  alloy,  as  the  cost  is  slight  and  the  prepared  alloy  is  then  avail- 
able when  wanted.  It  has  been  stated  that  zinc  volatilizes  very 
readily  from  solders.  This  is  quite  contrary  to  the  author's  findings. 
The  small  percentage  of  zinc  as  given  in  the  formulae  herein  is 
quite  stable  after  remelting  several  times.  The  authors  who  claim 
this  strong  volatilization  of  zinc  may  have  been  dealing  with  a 
solder  of  unknown  constitution  in  which  they  suspected  zinc  but 
which  probably  contained  a  percentage  of  cadmium  which  vola- 
tilizes quite  readily. 

REFRACTORY   MATERIALS.     INVESTMENT    COMPOUNDS 
FOR    SOLDERING. 

The  normal  contraction  of  gold  from  the  molten  to  solid  state  is 
approximately  2  per  cent.  The  contraction  of  gold  solder  is  prac- 
ticall>'  the  same,  although  some  of  the  constituents  have  a  higher 
contraction  than  gold,  but  when  combined  in  an  alloy  the  movement 
is  practically  the  same. 

While  possibly  there  may  be  a  slight  difference  between  the 
contraction  of  solder  and  gold,  a  considerable  contraction  occurs 
nevertheless,  and  is  the  cause  of  a  great  deal  of  trouble. 

A  number  of  soldering  investment  compounds  on  the  market  arc 
claimed  b>'  the  manufacturers  to  possess  neither  expathsioii  nor 
contraction,  and  therefore  perfect.  Granting,  for  the  sake  of  the 
argument,  that  such  is  the  case,  we  still  have  the  contraction  of 
solder  to  contend  with,  antl  how  arc  we  to  produce  a  soldered 
bridge  or  denture  that  will  fit  and  go  into  place  accurately,  when  a 
mimber  df  the  units  in  the  work  have  been  drawn  together  by  the' 
roiitra<tion  of  the  solder  '! 

rnfortiniatcly,  we  have  not  merely  the  contraction  of  the  solder 

to  contend  with,  but  we  have  a  niiicli  i -c  prolific  cause  of  disaster. 

For  example,  we  have  a   number  of  completed   sections,  such  as 
castings,  to  join  together  where  but  a  very  small  (piantity  of  solder 
2.5 


586 


DENTAL  METALLURGY 


is  to  be  used,  and  yet,  after  soldering,  we  find  that  the  finished  piece 
is  contracted  and  distorted  and  will  not  go  into  position.  The  fact 
of  the  matter  is  that  practically  all  the  commercial  compounds 
shrink  upon  heating,  when  brought  up  to  the  proper  temperature 
for  soldering. 

In  some  commercial  investment  compounds  the  shrinkage  is 
extremely  high,  fully  6  or  7  per  cent.,  so  it  is  evident  that  the 
principal  cause  of  the  trouble  lies  not  so  much  in  the  actual  contraction 
of  the  solder,  as  it  does  in  the  great  contraction  of  the  average  invest- 
ment, even  before  the  case  is  quite  hot  enough  to  apply  the  solder. 


Fig.  652 

Fig.  652  shows  an  ordinary  simple  bridge  assembled  and  ready 
for  investment.  The  porcelain  facings  are  spaced  as  per  instruc- 
tions from  time  immemorial.  Fig.  653  shows  the  case  invested 
and  the  distinct  spacing  of  the  backings. 

The  case  is  then  heated,  and  if  an  examination  of  the  investment 
is  made  with  a  magnifying  glass,  just  before  placing  it  on  the  sol- 


FiG.  653 


dering  block,  it  will  be  noticed  that  the  units  have  beeri  drawn 
together,  as  in  Fig.  654,  and  when  the  case  is  soldered  and  cooled, 
the  facings  are  very  apt  to  be  checked,  on  account  of  having  been 
brought  together  into  very  strong  contact. 


REFRACTOR Y  MA  TERIA LS 


387 


When  attempting-  to  place  l)ack  on  the  cast,  difficulty  is  encoun- 
tered, but  as  the  })laster  yields,  the  bridge  is  forced  down  and  then 
becomes  evident  the  loss  of  the  contact  points,  as  illustrated  in 
Fig.  (555. 


Fig.  654 

This  discrepancy  will  not  be  considered  by  some  operators  as  a 
serious  factor.  In  fact  those  who  solder  directly  on  the  cast  destroy 
the  evidence  for  the  time  being.  If  it  is  a  fixed  bridge,  it  is  forced 
home  some  way  or  other  and  let  go  at  that,  but  on  theother  hand, 
if  a  removable  bridge,  even  as  small  in  dimension  as  the  one  illus- 
trated, it  is  practically  impossible  to  place  it  in  position,  and  the 
matter  is  a  most  serious  one,  as  a  good  many  operators  have  found. 


Fig.  655 


Some  writers  advocate  com])leting  the  dummies  and  then  placing 
them  in  perfect  contact  to  prevent  the  shrinkage  of  the  solder  used 
to  unite  the  sections.  This  is  practically  impossible,  because  the 
metallic  units  arc  infinitely  stronger  than  the  investment,  and 
expanding  imder  lu-at  will  invariably  split  the  investment  (see  Fig. 
()50)  and  thus  often  cause  a  serious  distortion  in  the  soldered  piece. 

There  seems  to  have  been,  as  a  search  of  the  literature  has  shown, 
al)solutely  no  consideration  given  to  the  movement  of  the  refractory 
mass  that  holds  the  parts  ///  .vV//  during  llic  |)nliiiiinary  heating 
and  final  soldering  operations. 


388  DENTAL  METALLURGY 

The  author's  aim  in  experimenting  has  been  not  merely  to  pro- 
duce an  investment  compound  that  would  merely  not  shrink,  but 
one  that  would  actually  expand,  move  in  unison  with  the  solid 
invested  metal  and  spread  the  units  sufficiently  so  that  when  a 
reasonable  amount  of  solder  is  flowed  to  connect  the  units,  the 
contraction  of  the  total  piece  woidd  he  neutralized  by  the  expansion 
of  the  investiment. 


Fig.  656 

Before  attempting  to  formulate  an  investment  compound  pos- 
sessing such  properties,  it  is  necessary  to  consider  the  chemical  and 
physical  properties  of  refractory  materials  that  may  be  employed 
in  the  compounding  of  investment  materials. 

In  one  of  the  most  "  popular"  books  on  crown  and  bridge- work,^ 
the  following  appears: 

"Many  substances  may  be  used  in  combination  with  plaster  of 
Paris,  which  is  necessarily  the  basis  because  imparting  the  property 
of  crystallization,  and  which  must  be  incorporated  to  the  extent  of 
at  least  50  per  cent. 

"  The  remaining  proportion  may  be  then  composed  of  such 
materials  as  will,  by  virtue  of  their  characteristics  and  physical 
properties,  meet  such  requirements.    The  following  are  serviceable: 

Powdered  silex,  Pulverized  pipe  clay, 

Fine  asbestos,  Powdered  fire  brick. 

Beach  sand.  Magnesium  oxide. 

Marble  dust,  Pumice  stone. 

"A  combination  of  any  of  these  ingredients  in  varying  propor- 
tions with  the  proper  quantity  of  plaster  will  usually  possess  the 
necessary  qualities,  etc." 

Before  even  considering  a  compound  of  expanding  properties,  it 
is  well  to  thoroughly  understand  the  properties  of  plaster  of  Paris 

1  Goslee's  Priticiplcs  and  Practice  of  Crown  and  Bridge-work,  pp.  36-.37. 


REFRACTORY  MATERIALS  389 

and  the  other  materials  enumerated  in  tlie  list  of  suitable  refrac- 
tories, in  order  to  see  if  it  is  possible  to  even  produce  an  investment 
comi)ound  that  will  at  least  not  .shrinlc  under  heat. 

Plaster  of  Paris.— Plaster  of  Paris,  CaS04  (calcium  sulphate) 
is  made  by  burning  gypsum  rock.  In  the  process  of  burning,  most 
of  the  water  is  dri\en  ofl".  The  phenomena  of  recombining  with 
water  and  crystallizing  is  well  kno\Mi  and  need  not  be  discussed 
here.  It  is  universally  used  as  the  binder  for  all  investment  com- 
pounds used  both  for  soldering  and  casting.  It  shrijiks  very 
considerably  upon  heating,  but  for  want  of  a  better  material  must 
be  employed. 

The  more  plaster  used  in  an  investment  compound,  the  harder 
the  resultant  mass  will  be,  and  the  iiiore  s-hrinkage  w^ll  take  place. 
As  will  be  shown  subsequently,  any  such  proportion  as  the  oi)  per 
cent,  mentioned  by  the  author  quoted  is  absolutely  out  oj  question 
because  it  has  been  found,  so  far,  impossible  to  compensate  for  the 
contraction  of  the  binder,  by  the  addition  of  any  other  material, 
even  if  possessing  the  property  of  expansion. 

Powdered  Silex. — Silex  is  the  commercial  term  applied  to  silicon 
dioxide  (SiO-.j  which  is  the  main  constituent  of  rocks,  stones,  clays 
and  many  other  minerals.  A  great  deal  of  it  is  also  found  in  a  free 
state  and  in  the  form  of  quartz,  rock  crystal,  flint,  opal,  chalcedony, 
etc.  The  so-called  silex  is  often  practically  pure  Si02.  However, 
different  ^■a^ieties  of  silicon  dioxide  exist,  and  although  all  of  a  similar 
chemical  composition,  they  possess  varying  physical  properties. 

Silica  obtained  from  quartz  or  rock  crystal,  consists  of  sharp 
crystalline  particles  and  possesses  a  high  specific  gravity,  2.0  to  2.8. 
It  expands  considerably  upon  heating,  but  loses  this  property  grad- 
ually upon  reheating  frequently  or  fusing  completely.^  The  melting 
point  of  pure  silica  is  approximately  3200°  F. 

Another  variety  of  silica  that  exists  quite  as  frequently  as  the 
crystalline,  is  an  amorphous  form  which  j)ossesses  a  lower  specific 
gravity,  2.2  to  2.4.  It  has  very  little  expansion  upon  heating,  and 
some  varieties  of  the  same  type  do  not  expand  at  all. 

Still  a  third  variety  exists  in  a  tabular  form  and  is  extremely 
light  and  porous.  It  is  known  as  diatomaceous  earth  or  kieselguhr. 
Its  .specific  gravity  is  1  .(>  to  I  .S.    It  is  mined  in  v<-r\  great  (juantities 

'  Ut«imil«  made  of  fiistjd  «ili<-ii  art;  rcplaciiiK  plaliiiuiii  ware  to  a  Kroat  extent 
in  chcmir-al  work.  Ah  the  foeffifient  cxpanHion  i«  very  Mniall  (().()()0()(J0.'i4  jjcr  °  ('.) 
it  i.-i  jKiMrtiMe  to  .tuhjerl  »riicihle«.  cuhmtoU-h.  ctr-..  to  rapid  cliaiiKCH  of  tcin))oraturo 
wiihr.iit  danKCT  of  l.rcakaKc  Apparatus  «tiital)lc  for  dental  purposes  i.s  manufac- 
tiir«"d  l»y  tlie  Tlierriial  Syiidi<:ilc  F>l<i.,  of  N'cw  Vork. 


390 


DENTAL  METALLURGY 


and  used  very  extensively  as  a  heat-insulating  agent,  but  con- 
tracts very  strongly,  and  therefore  is  totally  unfit  for  use  as  part 
of  a  dental  refractory  compound. 

As  stated  before,  these  various  forms  of  silica  can  be  obtained  in 
almost  a  pure  state  and  are  alike  chemically,  but  the  term  "pow- 
dered silex,"  means  nothing  unless  a  particular  type  is  specified, 
and  the  individual,  who  is  not  conversant  with  the  matter,  is  as 
likely  as  not  to  purchase  and  use  a  grade  of  least  expansion.  The 
crystalline  variety,  of  high  specific  gravity,  expands  under  heat  con- 
siderably, and  in  this  fact  lies  the  solution  of  the  whole  problem. 

A  mixture  of  50  per  cent,  plaster  of  Paris  and  50  per  cent,  silica, 
even  if  the  latter  is  of  the  variety  possessing  the  highest  expanding 
properties,  contracts  very  considerably  when  brought  up  to  the 
temperature  required  for  soldering  or  casting  operations. 

In  order  to  be  brief,  the  author  will  state  that  all  the  other  items 
in  the  list  of  suitable  materials  have  a  positive  shrinkage,  with  the 
exception  of  beach  sand.  The  objection  to  the  latter,  is  the  fact 
that  it  is  often  quite  impure'  and  the  iron  and  alkalies  that  form 
the  major  portion  of  the  impurities  usually  act  as  a  flux,  and  thus 
lower  the  melting  point. 

It  is  well  to  state  that  magnesium  oxide  and  marble  dust,  which 
latter  is  of  course  calcium  carbonate,  are  subject  to  a  particularly 
strong  contraction  under  heat. 


Fig.  657 


Fig.  658 


Fig.  657  illustrates  the  comparative  shrinkage  of  one  of  the  best 
commercial  compounds  obtainable.  A  considerable  space  will  be 
noted  between  the  mass  of  investment  and  the  rim  of  the  metallic 
ring  in  which  it  was  placed  after  mixing,  permitted  to  set,  and  heated 
to  soldering  temperature. 

Fig.  658  (in  cross  section)  shows  even  more  clearly  the  contrac- 
tion after  heating  when  a  straight  edge  is  placed  across  the  top  of 
the  flask. 


kEFRACTORY  MATERIALS  391 

To  summarize  the  whole  proposition,  the  author  will  state  that 
in  order  to  produce  an  iiiM'.stnwnt  compound  that  not  only  does  not 
shrink,  but  actually  expands  sufficiently  to  follow  the  movement  of  a 
red  hot  ring,  that  it  is  necessary  to  use  a  grade  of  silica  as  pure  as  pos- 
sible and  of  the  highest  e.vpansion,  which  means,  of  course,  a  grade 
of  silica  from  the  quartz  group,  and  a  grade  of  plaster  of  Paris  of 
the  least  contraction}  As  previously  mentioned,  any  such  proportion 
as  50  per  cent,  plaster  cannot  be  used,  because  the  expansion  of  the 
best  silica,  great  as  it  is,  is  not  sufficient  to  compensate  for  even  the 
shrinkage  of  the  plaster.  Hence,  a  loicer  percentage  of  plaster,  and  a 
higher  percentage  of  silica  must  he  used. 

FORMULA    FOR   INVESTMENT    COMPOUND    (SOLDERING). 

Per  cent. 

Plaster  of  Paris  (Excelsior  Brand  No.  3)  33.0 

Silica  (Fine)  (F.  F.  F.)  45.0 

Silica  (coarser)  (M.  C.)         22.0 

Total ■.      100.0 

A  compound  made  according  to  this  formula  will  he  found  to 
expand  upon  heating  to  soldering  temperature,  sufficiently  to  fill  a 
red  iiot  ring,  as  in  Figs.  O't^  and  OOO. 


Fig.  6.59 


Fi(i.  OGO 


This  property  of  expansion  is  sufficient  to  counteract  ilie  conf ruc- 
tion of  a  normal  bulk  of  solder.  Furthermore,  thi.s  expansion  is  suffi- 
cient to  follow  the  movement  of  in  rested  metailir  sectiinis  that  hare 
been  previously  completed.  This  compound  sets  promptly  and  is 
sufficiently  strong  to  hold  the  invested  parts  in  situ  firmly.  It 
will  withstand  the  action  of  hoiling  water  (when  washing  out  the 
wax)  without  disintegration. 

'  It  in,  no  doubt,  well  known  that  fine  plaster  contracts  more  than  coarso  plaster 
wh«n  Hiihjected  Ui  heat.  Most  of  tlio  coarsi-  l)nil<iin>?  plasters  are  rather  uniniiforin 
and  do  not  posw-HH  the  hindiiiK  i)ow(!r  of  the  finer  plasters.  The  Krade  seh-ctiMJ  i.« 
quite  uniform  and  not  too  coarse  to  (in-vent  efricient  hindini.':  r)f  the  mass. 


392  DENTAL  METALLURGY 

Dr.  Peeso  has  long  ago  demonstrated  the  great  importance  of 
not  soldering  work  directly  on  the  cast.  The  work  should  be  so 
assembled  that  the  waxed-up  structure  may  be  removed  from  the 
cast,  which  is  made  of  plaster  of  Paris,  or  a  more  durable  material, 
such  as  "Artificial  Stone"  (made  from  the  author's  formula),  and 
then  transferred  to  the  investment  compound.  After  soldering,  the 
work  may  be  placed  back  on  the  cast,  which  is  intact,  and  required 
corrections  can  be  made  by  grinding  or  trimming  here  and  there 
before  the  structure  is  even  tried  in  the  mouth. 

Of  course  the  author  has  made  numerous  and  exhaustive  experi- 
ments to  determine  the  properties  and  behavior  of  various  refrac- 
tory materials,  and  it  is  important  that  the  grades  of  silica  and 
plaster  specified  be  used. 

As  the  reader  can  deduct  from  the  preceding,  the  terms  silica 
and  plaster  of  Paris  mean  very  little,  because  while  the  different 
grades  of  silica  are  practically  alike,  chemically  they  differ  very 
materially  physically.  To  the  author's  knowledge,  it  is  possible  to 
purchase  at  least  three  or  four  hundred  brands  of  plaster  and  over 
a  thousand  distinct  grades  of  silica  with  varying  percentages  of 
impurities  and  varying  sizes  of  particles.^ 

There  is  no  intention  to  claim  that  this  is  the  last  work  on  the 
subject.  No  doubt,  other  experimenters  will  succeed  in  producing 
as  good  or  even  a  better  compound  with  other  grades  of  material. 

Investment  Compounds  for  Casting. — The  elements  of  error, 
caused  by  the  physical  behavior  of  the  metallic  alloys  and  the 
refractory  materials  utilized  in  the  casting  process,  are  quite 
analogous  to  the  conditions  that  exist  in  the  soldering  process. 
Gold,  no  matter  how  alloyed,  so  far  as  present  knowledge  of  the 
subject  indicates,  does  contract  in  the  transition  from  the  fluid  or 
plastic  state  to  the  solid  or  frozen  state,  and  an  inlay  investment 
compound  that  possesses  the  property  of  expansion  will,  at  least  in 
measure,  compensate  for  the  contraction  of  gold. 

It  is  not  the  author's  aim  her'e  to  exhaustively  discuss  casting 
problems  in  general.  He  simply  wishes  to  suggest  a  formula  for 
what  he  considers  a  better  investment  compound  than  is  purchas- 
able, and  to  point  out  some  of  the  physical  phenomena  of  existing 

1  The  materials  used  by  the  author  were  obtained  from  W.  B.  Daniels,  252 
Front  Street,  New  York  City,  who  is  a  dealer  in  minerals  and  chemicals.  He 
will  supply  the  various  ingredients  for  both  the  soldering  and  casting  compounds 
in  quantities  suitable  for  the  requirements  of  the  practitioner.  Of  course  it  must 
be  remembered  that  such  comparatively  cheap  materials  are,  as  a  rule,  sold  by  the 
ton  or  car  load.  Hence,  Mr.  Daniel's  willingness  to  furnish  these  materials  in 
small  quantities  at  a  moderate  price  deserves  commendation. 


REFRACTORY  MATERIAL.'^  393 

conditions.  Before  discussing  the  t'ornnila  it  is  well  to  first  con- 
sider some  of  the  conditions  that  have  to  be  dealt  with.  We  have 
not  only  the  contraction  of  gt)ld  to  contend  with,  but  we  also  have 
the  contraction  of  the  wax,  and  that  is  a  most  serious  factor  indeed. 
The  contraction  of  wax  ift  nftnally  prodnctive  of  a  greater  degree  of 
error  than  the  actual  contraction  of  gold. 

This  subject  has  been  covered  most  thoroughly  by  Dr.  C.  S. 
\  an  Horn  of  Bloomsburg,  Pa.,  in  his  articles  in  the  Dental  Cosmos,^ 
and  his  conclusions  are  yet  to  be  contro\'erted. 

The  conditions,  which  he  successfully  corrects,  are  the  following : 
After  the  removal  of  a  ica.v  pattern  from  the  month,  at  body  temperature, 
it  contracts  considerably  upon  reaching  room  temperature  and  still 
more  when  invested  with  cold  water.  His  method  consists  of  invest- 
ing the  pattern  at  approximately  110°  F.,  which  increase  in  tem- 
perature not  merely  compensates  for  the  contraction  of  the  wax,  but 
also  expands  the  wax  to  almost  completely  counteract  the  shrinkage 
of  the  gold. 

In  addition,  he  uses  an  expanding  investment  (made  from  the 
author's  formula),  and  the  total  expansion  of  the  wax,  coupled  with 
the  expansion  of  the  investment,  enables  Dr.  \an  Horn  to  produce 
the  most  accurate  fitting  inlays  the  author  has  ever  seen.  A 
study  of  Dr.  Van  Horn's  technic  will  am])ly  repay  anyone  who  is 
desirous  of  obtaining  better  results. 

Dr.  James  G.  Lane,'-  of  Philadelphia,  was  among  the  first  to 
point  out  the  value  of  silica  as  an  ingredient  of  inlay  investment 
compounds,  on  account  of  its  expansion  and  consequent  ability  to 
counteract  the  contraction  of  plaster  of  Paris  (the  binder).  The 
formula  that  he  used  (plaster  25  per  cent,  and  silica  75  per  cent.) 
expands  considerably.  In  addition.  Dr.  Lane  was  also  among  the 
first  to  point  out  the  fact  that  a  hot  mould  was  stronger  than  one 
that  was  heated  and  allowed  to  cool. 

In  the  utilization  of  the  casting  process,  there  are  a  great  many 
important  factors  to  be  considered,  among  them  the  fusing  point 
of  the  investment  com})ound  which  constitutes  the  mould;  the  relation 
of  this  degree  of  fusibility  to  the  temperature  of  the  mould  at  the  time 
the  molten  metal  eiders  it;  the  temperature  of  the  nudten  metal  at  the 
tim£  it  enters  the  mould  mid  the  pressure  used  to  force  the  fnolfeu 
metal  into  the  mould. 

'  Dental  CoKnioH,  1»11,  pp.  (id),    172,  110'.).      1912,  \y\>.  S!)(),  '.)7:{.      I9H,  p.  '.tlO. 

'  S<'o  piiporH  of  .J.  Ct.  LaiH-  in  Doiital  fosinoH  juul  Dciiliil  Dinost,  lOlO  1  I.  Also 
M.  A.  Wiinl  in  Dfiitui  Co.sino.s.  These  coiilrilmtioiiH  arc  very  iiitorcslifiK  ;iii<l  llic 
inoxt   v;ilii:il»lc  that   have  appe.-ired  piTlriiiiirm  to  tlie  siiliject. 


394  DENTAL  METALLURGY 

The  fusing  point  of  an  investment  compound,  made  of  plaster 
of  Paris  and  pure  silica,  is  under  3000°  Y.  Some  of  the  commercial 
investment  compounds,  which  are  made  with  impure  silica  con- 
taining a  considerable  percentage  of  iron  and  feldspar,  which  latter 
contains  alkalies  such  as  sodium  and  potassium,  are  often  consider- 
ably lower  fusing.  Consequently,  when  superheated  gold  is  cast 
into  such  a  comparatively  fusible  investment,  a  partial  union  is 
bound  to  take  place,  with  the  consequence  that  the  gold  partly 
unites  with  the  investment,  and  the  resultant  casting  is  quite  rough 
and  inaccurate. 

The  strong  possibility  of  such  a  condition  as  described  leads  the 
author  to  state  his  opinion  on  that  apparently  never-ending  con- 
troversy regarding  the  casting  of  gold  in  a  hot  or  cold  flasJ:.  This 
point  has  been  argued  time  and  time  again,  some  operators  claiming 
that  they  obtain  better  results  by  casting  into  a  hot  flask,  and  others 
maintaining  the  reverse.  In  order  to  discuss  the  subject  intel- 
ligently, we  must  also  bear  in  mind  the  degree  of  heat  that  is  utilized 
for  melting  the  metal  to  prepare  for  its  entrance  mto  the  mould. 

Let  us  first  consider  the  following: 

Hot  or  Cold  Mould. — Using  the  iUymiimting  gas  and  compressed 
air  blow-pipe. 

We  shall  discuss  this  phase  first  because  the  great  majority  of 
castings  are  accomplished  by  using  the  ordinary  gas  and  air  blow- 
pipe. The  maximum  temperature  that  it  is  possible  to  produce 
with  artificial  gas  and  compressed  air  is  approximately  2450°  F. 
The  temperature  of  the  investment  in  the  casting  ring  when  red 
hot  is  about  1300°  F.  If  this  red  hot  flask  is  placed  on  the  castiug 
apparatus  and  the  quantity  of  gold,  say  5  dwts.,  placed  in  the  cru- 
cible, it  will  take  about  two  and  a  half  minute's  exposure  to  an 
efficient  blow-pipe  flame,  to  bring  the  gold  to  the  proper  state  of 
fluidity  to  enter  the  mould.  In  the  meantime,  the  red  hot  mould 
(on  the  casting  apparatus)  has  cooled  considerably,  and  the  actual 
temperature  of  the  cavity  in  the  mould  at  the  time  the  gold  enters 
it  can  be  safely  calculated  not  to  exceed  900°  F.  Therefore,  casting 
into  a  "red  hot  flask,"  with  an  ordinary  gas  and  air  blow-pipe,  is 
done  with  the  mould  not  red  hot,  but  at  a  temperature  approxi- 
mately 900°  F. 

In  casting  into  a  so-called  "cold"  flask  using  the  same  blow-pipe 
and  quantity  of  metal,  it  wiU  be  found  that  it  takes  longer,  say 
four  minutes,  to  bring  the  metal  into  a  state  of  fluidity,  and  although 
the  flask  is  at  room  temperature  when  the  process  of  melting  the 


REFRACTORY   MATERIALS  395 

gold  is  started,  the  subjection  of  the  mould  to  the  Hame  of  the 
efficient  bIow-{)ipe  for  a  period  of  tq)proxiniately  four  minutes 
raises  the  temperature  of  the  mould  to  an  extent  of  nearly  7()(J°  F, 
Therefore,  when  it  is  attempted  to  make  a  casting  with  the  ordinary 
gas  and  air  blow-pipe  in  a  so-called  "cold  flask,"  the  temperature 
of  the  mould  at  the  time  the  gold  enters  it  is  approximately  7(J(J°  F. 

Upon  considering  both  conditions  and  comparing  the  tempera- 
ture of  the  moulds,  namely  900°  and  700°  F.,  it  will  be  readily 
seen  that  there  is  comparatively  little  difference  between  the  two 
at  the  actual  time  that  the  casting  is  done,  and  consequently  both 
the  "hot  mould"  and  "cold  mould"  advocates  are  right,  strange 
as  that  may  appear,  providing  of  course,  that  the  ordinary  gas  and 
air  blow-pipe  is  employed. 

The  author's  experiments  along  this  line  have  shown  conclusively 
that  it  is  hardly  possible  to  superheat  the  gold  with  an  ordinary  gas 
and  air  blow-pipe  or  bring  the  gold  to  such  a  temperature  that  it 
will  unite  with  the  investment  at  any  stage  of  the  procedure  and 
it  is  the  author's  firm  opinion  that  in  the  hands  of  the  careless  or 
inexperienced  operator,  the  ordinary  gas  and  air  hlow-jnpe  is  a  posi- 
tive insurance  against  superheating  the  gold,  and  therefore  insures  a 
casting  satisfactory-,  at  least  as  far  as  errors  consequent  to  the 
superheating  of  gold  are  concerned. 

Hot  or  Cold  Mould. — Using  illuminating  gas  and  nitrous  oxide 
or  oxygen  hlow-ptpe. 

Here  we  have  a  totally  different  and  quite  often  a  dangerous 
condition  to  contend  with.  While  the  ordinary  gas  and  air  blow-pipe 
is  capable  of  i)roducing  temperatures  only  somewhat  beyond  24(M)° 
F.,  it  is  possible  to  obtain,  without  difficulty,  3400°  to  35!/()°  F. 
from  nitrous  oxide  and  illuminating  gas  and  over  4000°  F.  from  pure 
oxygen  and  illuminating  gas.  It  may  be  well  at  this  time  to  call 
attention  to  the  fact  that  the  often  used  term  "  oxyhydrogen" 
is  incorrect  when  used  in  connection  with  illuminating  gas  because 
of  the  fact  that  in  order  to  produce  an  oxyhydrogen  flame  it  is 
necessary  to  have  both  oxygen  gas  and  h\drogen  gas,  whereas 
ordinary  illuminating  gas  contains  less  than  half  of  its  volume 
of  hydrogen,  and  the  balance  is  principally  methane  (carbon,  etc.). 

It  is  very  difficult  to  avoid  superheating  gold  when  applying 
such  extreme  temperatures,  and  extreme  cauti(in  must  be  exercised 
by  the  oi>erator. 

As  a  rule,  the  cold  flask  is  indicated  when  using  extreme  temi)era- 
tures  for  melting  the  gold,  because  the  gold   melts  very   rapidly 


396  DENTAL   METALLURGY 

(15  to  20  seconds),  and  comparatively  little  heat  is  transmitted 
to  the  mould.  The  mould  is  then  comparatively  cool,  and  even  if 
somewhat  superheated  gold  is  cast,  it  is  not  so  apt  to  unite  with  the 
investment  as  when  both  the  gold  and  the  mould  are  superheated. 

TJie  author  has  very  often  made  failures  of  castings,  on  account 
of  superheating  the  gold,  and  he  wishes  to  impress  strongly  the  fact 
that  extreme  caution  must  be  exercised  in  this  connection. 

The  nitrous  oxide  or  oxygen  and  gas  blow-pipe  offers  advantages 
over  the  ordinary  gas  and  air  blow-pipe  as  a  means  of  producing 
heat  rapidly,  but  the  maximum  temperature  attainable  with  the 
ordinary  gas  and  air  blow-pipe  acts  as  a  sort  of  an  insurance  against 
superheating,  and,  in  fact,  if  efficiently  used  produces  satisfactory 
casting  results  in  all  ordinary  operations. 

One  of  the  most  prolific  causes,  in  fact,  probably  the  greatest 
cause  that  is  productive  of  faulty  castings,  is  the  excessive  pressure 
used  in  forcing  metal  into  the  mould.  The  principal  reason  for  this 
is  due  to  the  fact  that  in  the  majority  of  casting  apparatus  there 
is  no  provision  for  obtaining  a  definitely  measured  and  indicated 
amount  of  force.  It  takes  just  so  much  and  no  more  pressure  to 
force  gold  into  a  given  mould,  and  hold  it  there  until  solidification 
begins.  Excessive  pressure  will  not,  under  ordinary  conditions, 
prevent  the  normal  contraction  of  gold,  because  the  moidd  into 
which  the  gold  is  cast  yields,  and  hence  will  distort  in  the  same  propor- 
tion as  excessive  pressure  is  applied.  It  may  be  true  that  a  pressure 
of  2000  pounds  per  square  inch  may  totally  prevent  contraction,  but 
where  is  the  mmdd  that  will  stand  that  pressuref 

It  is  unfortunate  that  more  operators  do  not  realize  the  true  value 
of  an  efficient  casting  apparatus  such  as  the  Taggart,  and  the  false 
economy  resulting  from  the  use  of  an  intrinsically  faulty  or  make- 
shift device. 

B}^  using  a  grade  of  silica  of  maximum  expansion,  and  a  grade  of 
plaster  of  minimum  contraction,  it  is  possible  to  produce  an  invest- 
ment compound  as  follows: 

FORMULA    FOR   INVESTMENT    (CASTING). 

Parts. 

Plaster  (Excelsior  Brand  No.  3) 29.0 

Silica  (Fine)  (F.  F.  W.) 71.0 

Total 100.0 

The  plaster  is  the  same  as  is  used  in  the  soldering  investment. 
The  silica  is  similar  to  the  fine  grade  utilized  in  the  soldering  invest- 
ment formula,  but  it  is  purified,  and  combines  with  water  readily 


REFRACTORY  MATERIALS  397 

without  releasing  dirt,  scum,  etc.,*  and  consequent  bubbles.  An 
investment  made  from  this  formula  will  l)e  found  to  expand  slightly 
more  than  Dr.  Lane's  formula,  although  the  plaster  of  Paris  content 
is  higher,  and  for  the  same  reason  somewhat  stronger,  and  more 
resistant  to  excessi\e  pressure. 

Compounding  of  Investment  Materials. — It  is  a  well-known 
fact  that  \ery  few  commercial  in^•estment  compounds  are  uniform 
in  composition.  In  other  words,  although  the  manufacturers  claim 
that  their  formulae  are  adhered  to,  there  appear  \ariations  in 
batches  purchased  at  different  times.  This  is  due  to  the  fact  that 
insufficient  attention  is  paid  to  testing  the  different  batches  of  raw 
material,  and  also  to  the  faulty  compounding  due  to  the  large 
quantities  mixed  at  a  time.  One  commercial  preparation  has  been 
found,  on  the  contrary,  quite  uniform,  ff)r  the  simple  reason  that 
the  manufacturer  pays  especial  attention  to  the  testing  of  the 
raw  materials  and  compounds,  the  mixture  in  comparatively  small 
quantities  (200- .•')()()  lbs.  to  the  mix). 

In  mixing  the  plaster  of  Paris  and  silica,  it  is  not  necessary  to 
do  any  sifting,  because  the  specified  materials  may  be  obtained 
evenly  and  definitely  graded.  All  that  is  required  is  a  thorough 
mixture  icithout  excess ive  trituration. 

A  very  efficient  small  mixing  apparatus  may  be  obtained  from 
The  J.  II.  Day  ('o.,  Cincinnati,  Ohio.  It  is  known  as  the  "  Hunter" 
(experimental  size),  and  will  handle  from  seven  to  eight  pounds  of 
material.  The  ingredients  arc  weighed  out,  placed  in  the  container, 
and  the  a|)paratus  revolved  slowly  for  twenty-five  or  thirty  minutes. 
This  produces  a  uniform  and  intimate  mixture  without  crushing 
or  grinding  the  plaster.  This  point  is  very  important,  and  if  smaller 
cpiantities  are  mixed  in  a  mortar,  it  is  important  to  use  very  light 
pressure  in  order  not  to  crush  the  ])lastcr  particles.  The  mixed 
material,  of  course,  should  l)c  i)n)perly  stored  and  protected  against 
moisture. 

Investments,  Directions  for  Use. — The  soldering  investment 
should  be  mixed  quite  thick.  The  thicker,  the  better,  up  to  a  cer- 
tain limit,  of  course.  If  mixed  too  dry,  the  plaster-of-Paris  content 
does  not  obtain  sufficient  moisture  to  crystallize  i)roperly  and 
act  efficiently.  A  good  consistency  is  42  to  4.'^)  grammes  powder 
to  each   I.')  c.c.  water  or  27  dwts.  C^lVoy)  to  \  fluid  oz.  water. 

>  Uiililtlc.-'  ami  TmiIIi  proiliicol  iiixiii  atli-iiipliiiK  t<'  comliiiK;  iiiveisliiii-iit  coiiipouiKl 
ami  wa»<T,  arc  often  caiiHcd  li.v  dirt  or  hucIi  impurities  as  riiica,  etc.,  conlaiiicd  in 
tlic  silica. 


398  DENTAL  METALLURGY 

The  inlay  investment  should  be  mixed  in  a  proportion  of  35-36 
grammes  powder  to  15  c.c.  water,  or  23  dwts.  (Troy)  powder  to  ^ 
fluid  oz.  water.  This  quantity  is  sufficient  to  fill  an  ordinary  inlay 
flask. 

These  proportions  produce  a  mixture  that  allows  ample  time  for 
manipulation,  provided  considerable  time  is  not  spent  in  adding 
a  little  more  water,  a  little  more  powder,  etc.  The  setting  time  of 
the  -plaster  naturally  controls  the  setting  time  of  the  ichole  mixture, 
and  as  the  action  of  retarding  agents,  added  to  control  the  set  of  plaster 
is  sometimes  indefinite,  and  often  harmful,  it  is  advisable  not  to  attempt 
to  interfere  with  the  normal  setting  time  of  the  plaster. 

The  compound,  if  mixed  without  any  unnecessary  delay,  sets 
sufficiently  slow  for  all  ordinary  operations.  It  is  the  author's 
practice  to  have  on  hand  a  number  of  cork-stoppered  bottles  con- 
taining the  dry  compound  (weighed),  and  a  number  of  rubber-stop- 
pered vials  containing  water  (measured) .  The  accurately-measured 
powder  and  water  are  thrown  simultaneously  into  the  mixing  bowl, 
and  having  no  bubbles  or  froth  (as  with  graphite  compounds)^ 
to  contend  with,  the  mix  can  be  made  ready  for  use  in  from  30  to 
40  seconds,  thus  allowing  ample  time  for  coating  the  pattern  and 
imbedding  in  flask. 

This  method  is  superior  to  using  the  automatic  weighing  appara- 
tus furnished  by  some  of  the  compound  manufacturers,  as  they  are 
often  either  inaccurate  or  not  sufficiently  "flexible." 

It  is  not  advisable  to  attempt  to  invest  more  than  one  pattern 
at  a  time. 

Another  advantage  in  using  measured  and  stored  water  lies  in 
the  fact  that  it  is,  when  used,  at  room  temperature,  and  not  at 
hydrant  temperature,  and  the  room  temperature  water  does  not  induce 
a  further  contraction  of  the  wax  pattern  during  the  process  of  infesting. 

Heating  of  Investments. — The  soldering  investment  may  be 
heated  quite  promptly  upon  setting.  Boiling  water  does  not  affect 
it  materially  and  the  wax  may  be  washed  out  thoroughly,  the  case 
fluxed  and  immediately  placed  on  the  heat,  moderate  at  first  and 

'  Most  of  the  compounds  that  contain  flake  graphite  are  very  difficult  to  mix 
on  account  of  the  air  content  in  the  flakes  and  their  tendency  to  "float." 
Such  a  compound  requires  a  considerable  period  of  time  to  mix,  and  therefore  a 
retarded  plaster  is  usually  employed.  Nodules,  or  "ghosts"  on  castings,  occur 
frequently  because  the  material  is  not  "dormant"  until  "set."  One  manufacturer 
of  such  a  compound  claims  that  it  is  the  plaster  and  not  the  graphite  that  causes 
the  bubbles.  This  statement  appears  quite  contrary  to  the  facts.  Kerr's  "Graphite" 
Investment  is  made  with  previously-treated  graphite  and  it  is  the  best  graphite 
investment  that  the  author  knows  of, 


REFRACTORY  MATERIALS  399 

then  brought  up  quite  rapidly  to  a  good  red  heat  prior  to  the  actual 
solderiug  operation. 

It  IS  the  inefficient  and  inanfficient  heating  of  the  invested  leork 
that  is  partly  to  blame  for  the  "popular"  demand  for  "easy-flowing" 
solders.  Properly-heated  inrestments  facilitate  the  flow  of  normal 
or  even  high-fusing  solder. 

A  small  quantity  of  potassium  sulphate  or  sodium  chloride  may 
be  used  to  hasten  the  setting  of  the  investment,  but  that  is  rarely, 
if  ever,  necessary  because  it  sets  quite  promptly  if  mixed  to  the 
proper  consistency. 

The  inlay  investment  should  be  permitted  to  set  for  at  least 
thirty  minutes,  to  insure  a  fair  crystallization  (so-called  "initial 
set")  of  the  plaster.  The  flask  should  then  be  placed  over  a  low 
heat  and  kept  there  until  the  moisture  disappears  and  the  wax 
begins  to  diffuse  and  carbonize.  The  heat  is  increased  somewhat, 
during  the  latter  part  of  this  operation,  and  still  further  increased 
until  the  mould  is  brought  up  to  either  a  dull  red  heat  (for  cold 
mould)  or  a  bright  red  heat  (for  hot  mould). 

The  initial  stages  of  heating  must  be  at  a  temperature  that  will 
not  permit  the  wax  to  run  out  of  the  mould,  as  it  is  important  that 
the  wax  be  absorbed  in  the  mould.  Forced  heating  and  a  generation 
of  steam  during  the  initial  stages  of  the  drying  process  will  force 
the  wax  out  of  the  mould  and  produce  a  rough  interior,  which  in 
turn  will  show  its  effects  upon  the  casting,  the  resultant  casting 
being  rough,  incorrect,  and  usually  unfit  for  use.  It  is,  of  course, 
essential  to  confine  and  concentrate  the  (higher)  heat  in  order  to 
l)ring  the  mould  to  the  proper  temperature  within  a  reasonable 
jH'riod  of  time. 

Prolonged  heating  of  the  investment  is  even  more  dangerous 
than  underheating,  as  plaster  of  Paris,  which  is  the  binder,  shrinh 
in  proportion  to  the  time  that  it  is  exposed  to  heat.  The  total  heating 
operation  for  an  ordinary  mould  (inlay,  etc.)  should  not  exceed 
fifty  minutes  or  an  hour  at  most.  It  may  be  divided  into  three 
periods,  say  twenty-five  to  thirty  minutes  for  low  drying  heat, 
then  increased  somewhat  for  ten  to  fifteen  minutes,  and  finally 
subjected  to  the  highest  heat  for  not  more  than  from  ten  to  fifteen 
rniiMites. 

It  is  |>erniissible  not  to  heat  a  case  until  two  or  three  hours  after 
the  investment  has  been  mixed,  but  if  it  is  permitted  to  stand  for 
;i  day  or  two,  and  loses  all  moisture,  if  then  heated  and  cast,  the 
n>iilt;itit  casting  is  apt  to  be  very  jjoor.     It  is  hard  to  determine 


400  DENTAL  METALLURGY 

the  actual  principle  involved,  and  it  is  not  important  to  do  so,  but 
the  fact  does  exist.  In  addition,  under  such  conditions,  the  invest- 
ment is  very  apt  to  crack  or  split  upon  heating.  The  author  usually 
heats  and  casts  into  "green"  moulds,  but  has  found  that  a  dry 
mould,  if  moistened  prior  to  heating,  appears  to  behave  almost  as 
well  as  a  "green"  mould.  If  the  mould  is  only  a  few  hours  old  it 
is  moistened  slightly,  but  if  it  is  more  than  a  day  old,  it  is  placed 
in  water  until  saturated  to  the  extent  of  a  "green"  mould. 

Both  the  soldering  and  casting  investment  compounds  are  prac- 
tically immune  to  "checking"  or  ''cracking,"  even  under  the  most 
severe  heating  conditions.^ 

FLUXES. 

Fluxes  for  Soldering  and  Casting. — For  sweating,  soldering  or 
melting  metals  in  the  construction  of  bands,  crowns,  bridges,  or 
castings,  the  selection  and  use  of  the  proper  flux  or  fluxes  is  a  matter 
of  the  utmost  importance,  especially  if  the  metals  or  alloys  used 
are  oxidizable  or  volatile  when  subjected  to  heat. 

Ordinary  borax,  or  calcined  borax,  has  been  the  principal  flux 
used  for  this  purpose.  It  has  been  almost  universally  used  by 
jewelers,  and  the  dentist  has  followed  suit.  There  is,  however,  a 
considerable  difference  between  the  class  of  work  that  the  jeweler 
and  the  dentist  perform. 

In  dental  soldering,  we  use  higher  grade  solders  and  a  consider- 
ably higher  heat,  during  the  various  operations.  As  ordinary  borax 
melts  at  a  comparatively  low  temperature,  it  does  not  act  as  effi- 
ciently during  the  higher  temperature  stages  as  the  requirements 
demand.  The  tendency  of  borax  when  considerable  heat  is  applied, 
is  to  liquefy  strongly,  and  run  down  to  the  deep  portions,  leaving 
the  other  portions,  that  it  is  desired  to  solder,  insufficiently  pro- 
tected. Dr.  Peeso  recognized  this  long  ago  by  using  a  combination 
of  borax  and  boric  acid,  which  combination  melts  at  a  higher 
temperature  than  borax  alone,  does  not  liquefy  so  readily,  stays 
on  the  surface,  protects  the  work  longer,  and  is  more  efficient  in 
every  way. 

1  This  fault  is  inherent  in  most  investment  compounds;  the  causes  are  numerous 
and  principally  due  to  the  producers  ignoring  the  physical  laws  governing  the  selec- 
tion and  compounding  of  materials  for  the  purpose.  One  of  the  principal  errors  in 
this  connection  is  the  attempt  to  form  a  "concrete  like"  mass  without  realizing 
that  there  is  a  very  great  difference  in  the  behavior  of  dental  investment  compounds 
and  concrete  \ised  in  building  operations. 


FLUXES  401 

All  ffficifut  Hux  that  has  served  very  satisfactorily  in  the  author's 
hands  tor  a  considerable  period  of  time  is  the  following: 

FORMULA    FOR    SOLDIERING    FLUX. 

Tarts. 

C.  P.  Lorax  filass  (fused) -j-j  ^' 

C.  r.  Ijorif  iK-kU not  fused) ■^■'5  0 

C.  P.  silica 10^ 

Total 1"0  0 

The  ingredients  are  placed  in  a  clean  clay  or  sand  crucible,  and 
brought  to  a  fair  red  heat.  They  combine  quite  readily  and  when 
ciuite  fluid,  the  mixture  is  poured  intt)  cold  water.  As  this  glass  is 
quite  soluble,  it  must  be  removed  from  the  water  as  soon  as  possible, 
dried,  and  ])ulverized  to  ])ass  an  cSO  mesh  sieve.  It  ma>-  be  pul- 
verized without  difficulty,  as  the  particles  are  very  frail  and  brittle. 

This  flux  may  be  used  either  in  the  i)o\vdered  form  or  comi)ounded 
with  "  vaseline,"  to  form  a  paste,  or  dissolved  in  boiling  water  and 
the  saturated  solution  used.  In  the  liquid  form,  it  will  be  found 
suitable  for  all  general  oper-titions  where  the  work  can  be  heated, 
so  as  to  drive  off  the  moisture  and  thus  leave  a  coating  of  the  Hux, 
a«  in  bands,  crowns,  etc.  When  the  work  is  in  an  investment,  the 
grease  flux  will  be  found  most  useful,  as  it  may  be  applied  just  after 
the  case  is  washed  out  and  still  warm.  The  carrier  (vaseline)  flows 
down  into  the  deep  ])ortions  and  crevices,  carrying  the  i)articles 
of  flux  along.  The  ])o\v(lered  dry  Hux  can  be  used  on  invested  work 
under  the  blow-])ii)e  when  more  Hux  is  recpiired.  The  strips  of 
solder  can,  of  course,  be  coated  with  either  the  \k\\nd  or  the  grease 
flux,  and  heated  prioi'  to  use. 

This  solficriiiri  Jliix  in  n  jr.ncdvrctJ  j'onii  irill  also  he  used  <is  flie 
hdse  for  hutli  the  rrdiirin;/  and  oxidizing  Jlu.res  tu  he  discussed. 

It  is  important  that  the  forms  of  l)orax  and  boric  acid  speciHcd 
be  adhered  to,  because  of  the  variable  amount  of  water  that  these 
materials  contain  when  i)urcliase<l. 

The  formula  of  borax  glass  is  Xa-BiOv,  whereas  ordinary  borax, 
either  powdered  or  crystals,  contain  a  considerable  i)roi)()rtion 
of  water,  which  i>  evident  from  the  formula  XaoBiOy  +  U)Il2(). 
Therefore  the  borax  glass  is  |)referable  to  the  ordinary  borax  con- 
taining water,  becaUKc  it  occupies  much  less  space,  and  is  therefore 
more  convenient  to  handle  in  small  crucibles.  However,  if  ordinary 
borax  is  used,  the  water  content  must  be  calculated  and  jjrovided 
for  in  weighing  out  the  iiigicdicnts.  The  boric  acid  used  does 
I'll 


402  DENTAL  METALLURGY 

contain  water,  as  will  be  seen  from  the  formula  H3BO3,  because  it 
is  more  stable  than  the  fused  boric  acid  B2O3,  and  more  readily 
obtainable.  The  silica  should  be  pure,  and  in  the  form  of  a  fine 
powder,  so  that  it  may  combine  readily.  The  grade  (F.  F.  W.) 
used  in  inlay  casting  investment  is  quite  suitable. 

Reducing  Flux. — In  connection  with  the  casting  process,  it  is 
necessary  to  treat  buttons  of  gold  both  during  casting,  and  before 
recasting,  with  a  flux  that  will  take  care  of  the  acquired  impurities. 
Very  often  there  have  appeared  statements  to  the  efi^ect  that  a 
mixture  of  potassium  nitrate  and  borax  be  used  to  cleanse  buttons 
before  recasting.  This  statement  has  been,  in  a  good  many  cases 
to  the  author's  knowledge,  misunderstood.  Potassium  nitrate  is 
an  excellent  oxidizing  agent,  and  does  remove  base  metals,  but  its 
use  in  treatment  of  casting  buttons  is  contraindicated  because 
generally,  when  casting  gold  alloys  containing  copper,  etc.,  it  is 
desired  to  retain  the  base  metal,  the  copper,  in  a  reduced  metallic 
form,  and  not  in  an  oxidized  form.  Consequently,  if  a  flux  is  to  be 
used,  it  must  be  of  a  distinctly  reducing  nature. 

Reducing  fluxes  are  used  extensively  in  assaying  and  smelting 
operations,  and  their  properties  are  well-known.  In  the  case  of 
casting,  it  is  rather  difficult  to  utilize  all  the  benefit  that  may  be 
derived  from  a  reducing  flux,  on  account  of  the  difficulty  of  apply- 
ing same  to  the  molten  metal,  while  it  is  exposed  to  the  blow-pipe 
flame  which  blows  instead  of  drives  off  the  flux  almost  as  fast  as  it 
is  applied.  Therefore,  to  obtain  any  considerable  benefit  from  a 
reducing  flux,  it  is  necessary  to  not  merely  apply  same  while  the 
gold  is  fluid  under  the  blow-pipe,  but  also  to  sprinkle  an  additional 
amount  in  the  manner  described  in  the  following:  After  placing 
flask  on  casting  apparatus,  place  button  or  nuggets  of  gold  into 
crucible,  melt  without  flux  until  the  mass  of  gold  assumes  a 
spherioidal  form  and  completely  covers  the  sprue  hole.  Then 
apply  some  flux  by  sprinkling,  continue  the  melting  until  the  gold 
is  in  a  proper  state  of  fluidity  for  casting,  then  remove  flame,  add 
some  more  flux,  and  instantly  apply  the  casting  pressure. 

FORMITLA    FOR    REDUCING    FLUX. 

Parts. 

Soldering  flux  (base) • .      .        40.0 

Borax  glass 30.0 

Argol 25.0 

Animal  charcoal  . , .      .      .  5.0 

Total 100.0 


FLUXES  403 

Argol  is  the  commercial  term  for  crude  potassium  hitartrate 
KHC4H4O6  (cream  of  tartar)  and  has  a  higher  reducing  power 
than  piu-e  cream  of  tartar.  If  the  latter  is  used,  it  should  be 
increased  to  about  25  parts,  and  the  soldering  flux  and  borax  glass 
content  reduced  in  proportion. 

A  fliLx  of  this  character  will  practically  prevent  the  bringing  into 
the  casting,  of  oxidized  material,  and  can  be  used  to  advantage  in 
remelting  and  cleansing  buttons  of  gold  for  recasting. 

The  author's  procedure  for  this  operation  is  as  follows:  After 
a  casting  is  made,  the  residue  button  is  placed  into  hydrofluoric 
ac-id  for  fifteen  or  twenty  minutes,  removed  and  melted  with  the 
blow-pipe  on  a  charcoal  block,  using  the  reducing  flux,  which,  in 
addition  to  reducing  the  oxidized  copper  in  the  button,  combines 
with  the  silica,  traces  of  which  may  adhere  to  the  button.  After 
the  button  is  melted,  and  the  fliLX  used  has  segregated  into  a  globule, 
the  blow-pipe  is  removed  and  a  small  quantity  of  ammonium' 
cldoride  is  sprinkled  on  the  button.  As  soon  as  the  button  has 
solidified,  and  while  still  red  hot,  it  is  plunged  in  dilute  hydrochloric 
or  suli)huric  acid.  Most  of  the  glass  formed  by  the  flux  will  splinter 
off.  If  any  considerable  quantity  adheres,  it  may  be  removed  by 
l)oiliiig  in  the  same  acid. 

Oxidizing  Flux.— Potassium  nitrate  is  a  most  excellent  oxidizing 
agent  and  rem()\es  the  base  metals,  the  only  objection  being  the 
strong  fumes  which  are  given  off  during  the  melting  process. 
-Mthough  the  operator  should  rarely  attempt  to  do  refining,  it  is 
well  to  have  a  suitable  oxidizing  flux  that  will  not  give  off  the 
objectionable  fumes  characteristic  of  potassium  nitrate. 


FORMULA    FOR    OXIDIZINC    FLUX. 


Si)lr|crilltt  flux   (l);isc) 

l'')l:i.s.-.iiini  cliloraic 

Sodiiiiii  pfilxjratu •>5  0 


J'uits. 

55 .  U 
20.0 


Total 


100.0 


This  Hux  will  be  found  useful  for  revivifying  buttons  of  gold 
which  are  contannnated.  it  is  sufficiently  powerful  to  volatilize 
.such  inipurities  as  tin,  cadniiuni,  bismuth,  etc.  It  will  combine 
with  adherent  investment  compound  and  not  attack  copper  very 
.strongly,  .^.,  that  a  button  of  gold  that  has  been  u.sed  several  times 
and  is  quite  shiggi>li  and  dirty,  can  be  usually  brought  into  good 
shaijc  without  diffif  iilf\-. 


401  DENTAL  METALLURGY 

A  button  treated  with  this  flux  should  be  cleansed  in  acid,  as 
previously  described,  and  then  remeUed  with  the  reducing  flux 
prior  to  use  for  casting. 

In  cases  of  refining,  where  a  stronger  action  is  required,  the  potas- 
sium chlorate  and  sodium  perborate  can  be  increased  to  obtain  the 
same  efficiency  that  a  high  percentage  of  potassium  nitrate  would 
give  without  the  objectionable  fumes  characteristic  of  the  latter. 

It  is  expected  that  prepared  flux  made  according  to  the  formulae 
given  will  be  very  shortly  available  from  the  supply  houses.  Until 
such  time,  a  modification  of  the  soldering  flux  formula,  Avhich 
also  acts  as  a  base  for  the  reducing^  and  oxidizing  fluxes,  is  given 
herewith  for  the  benefit  of  those  who  have  not  the  facilities  for 
fusing  and  pulverizing  the  material.  These  ingredients  make  a 
flux  which  appears  to  work  much  more  satisfactorily  than  ordinary 
borax  or  any  of  the  secret  preparations  purchasable. 

FORMULA   FOR   SOLDERING    FLUX    (SUBSTITUTE). 

Parts. 

C.  P.  borax  glass 50.0 

C.  P.  boric  acid 43.0 

C.  P.  sodium  silicate  (dry  powder) 7.0 

Total 100.0 

This  is  mixed  thoroughly  in  a  mortar  and  must  be  ground  fine 
enough  to  pass  an  80  mesh  sieve. 

The  author  trusts  that  his  remarks  upon  the  importance  of  pro- 
ducing castings  with  all  the  metal  in  a  reduced  form,  and  not  in  a 
partially-oxidized  form,  will  be  given  some  consideration  by  the 
reader,  as  this  problem,  on  an  immeasurably  larger  scale,  has  been 
and  is  one  of  the  most  important  ones  in  the  application  of  indus- 
trial alloys,  and  is  being  coped  with  successfully. 

'  There  are  a  number  of  better-reducing  agents  than  those  suggested  by  the 
author,  used  industrially.  They  are  not  mentioned  because  of  either  difficulty  of 
application  under  casting  conditions,  or  on  account  of  not  being  obtainable  in 
small  quantities.  A  study  of  the  methods  used  in  deoxidizing  copper,  brass  and 
bronze,  is  suggested  to  those  particularly  interested. 


kEMOVABLE   HRllHlE-WORK  405 

Table  i\  .— meltixg  points  of  the  new  series  of  alloys  and 
standard  dental  golds. 

°F.                       Al.LOY.  o  C. 

2100     *-'Ela:^tic"'  (;..1(1 1150 

2975     *Plate  No.  1 1135 

Ut7.".     *Plate  No.  2 1080 

U»(3()       Type  4  Clasp 1070 

1945       Pure  Gold lOfi.'J 

194.-J     *rasting  Gold 'A" 1063 

194.")     *Casting  Gold  "B" 1063 

194.5       ''Green  Gold"  (App.  An  SO  per  cent.   A<i.  20  per  cent.)  1001 

1900     *CastingGold  '-B"         10.3.5 

1900       Light  22-K.  Plate 1035 

1860       Medium  22-K.  Plate 1015 

1860       Type  3  Cla.sp 1015 

182,5       Dark  22-K.  Plate 995 

1800     *Casting  Gokrr"         980 

1760       Light  20-K.  Plate 960 

173.5       Coin  Gold  (21. 6-K.) 946 

172.5       Type  2  Clasp 940 

1650     *Gold  Solder  No.  84 900 

162.5       Gold  Solder  for  22-K S80 

1600       Type  1  Clasp 870 

1550     *Gold  Solder  No.  76 840 

1525       Gold  Solder  for  20-K 820 

1450     *Gold  Solder  No.  68 785 

142.5        Gold  Solder  for  IS-K 77O 

The  ten  alloys-  innrked  "  *  "  eonfitlfitfe  the  new  series. 

They  are  all  uniform  in  color  with  the  exception  of  "Elastic" 

gold  which  is  similar  to  platinum  in  color  and  Casting  Gold  "  A  " 
which  i.s  similar  to  |)ure  gold  in  color. 


SOME    OF    THE    APPLICATIONS    OF    THE    NEW    SERIES 

OF    ALLOYS    IN    THE    PEESO    SYSTEM    OF 

REMOVABLE    BRIDGE-WORK. 

.\-  will  l)c  .seen  from  the  preceding  table,  the  series  of  alloys 
olfers  a  large  range  of  variation  in  melting  point,  over  the  ordinary 
alloys,  thus  facilitating  the  i)crforniancc  of  successive  soldering 
o|)crations. 

Construction  of  Bands,  Floors,  and  Inner  Caps.  As  has  been 
previously  stated,  coin  gold  is  the  most  suitable  alloy  for  the  con- 
struction of  bunds,  floors,  etc.  It  is  therefore  necessary  to  use 
coin  goM  or  its  ct|uivalcnt  in  the  uew  scries  of  alloys'.     The  band 


406  DENTAL  METALLURGY 

should  therefore  be  made  of  the  No.  2  i)late  (M.  P.  1975°  ¥.,  1080° 
C),  and  united^  by  soldering  with  the  next  lowest  fusing  alloy, 
namely,  Casting  Gold  ^'B"  (M.  P.  1900°  F.,  1035°  C). 

The  floor  is  also  prepared  of  No,  2  plate  and  soldered  to  the  band 
with  Casting  Gold  "  C"  (the  pliers  grasping  the  band  at  previously- 
joined  portion). 

The  method  will  make,  for  all  intents  and  purposes,  a  seamless 
cap.  The  melting  point  of  the  soldered  junctions  will  still  be  con- 
siderably above  that  of  coin  gold.  The  tube  may  then  be  attached 
with  the  No.  84  solder. 

Inner  caps  for  telescope  crowns  are  made  in  exactly  the  same 
manner.  As  the  hardness  and  tenacity  of  the  No.  2  plate  is  the 
same  as  that  of  coin  gold,  the  same  gauges  of  plate  are  to  be  used 
as  with  coin  gold.  The  casting  gold,  if  used  as  solder,  should  be  of 
practically  the  same  thickness  as  ordinary  gold  solder,  approximate 
28  gauge  B  &  S,  or  preferably  thinner  (30  to  32  g.). 

Outer  Half  Bands  and  Telescope  Crowns. — After  completing 
the  inner  cap  and  tube,  the  floor  is  made  of  No.  2  plate,  the  split 
pin  attached  to  it  with  No.  84  solder  and  the  half  band  fitted  and 
attached  with  84  solder. 

For  telescope  crowns,  the  outer  band  is  made  of  the  No.  2  plate 
and  the  joint  soldered  with  casting  gold  B.  The  wings  are  made  of 
No.  2  plate  and  soldered  to  the  band  with  Casting  Gold  "C."  The 
cusp  is  swaged  of  No.  1  plate  (higher  fusing  than  pure  gold),  filled 
with  Casting  Gold  "C"  in  the  same  manner  as  a  pure  gold  cusp 
is  filled  with  coin  gold,  and  attached  to  the  previously-completed 
outer  band  and  wings  with  No.  84  solder. 

If  the  cusp  is  to  be  cast,  Casting  Gold  "B"  or  "C"  should  be 
selected  according  to  the  blow-pipe  used,  and  attached  to  the  con- 
toured band  with  No.  84  solder. 

As  all  of  the  alloys  of  the  series  used  in  this  operation  are  of  the 
same  color,  and  the  No.  84  solder  is  actually  20-K.  fine,  there  will 
be  no  line  of  demarkation  evident  in  the  finished  work. 

Inlay  Abutments. — The  shell  for  the  inner  inlay  may  be  cast 
with  Casting  Gold  "D"  and  adapted  to  the  cavity  by  burnishing. 
The  tube  is  then  soldered  and  the  whole  completed  with  No.  84 
solder.  The  outer  inlay  matrix  can  then  be  made,  using  the  com- 
paratively soft,  but  high-fusing  plate-gold  No.  1,  and  Casting  Gold 
"C,"  instead  of  pure  gold  and  coin  gold. 

1  See  Dr.  Peeso's  method  of  band  preparation  for  sweating. 


REMOVABLE  BRIDGE-WORK  407 

Construction  of  Saddles.  The  saddles,  if  swa^vd  of  i)latiiiuni, 
may  he  reinforeed  with  ('astiii<;-  (lold  "H"  or  "(\"  instead  of  coin 
gold,  or  the  saddles  may  he  swaj^ed  of  No.  1  phite  (softer  than  No. 
2)  and  reinforced  with  ('asting  (Jold  "('."  If  the  saddles  are  to 
be  cast,  ('asting  Gold  "B"  or  "C"  slionld  be  selected  according  to 
the  blow-pipe  used. 

Construction  of  Dummies.— In  constructing  the  dummies  (if 
all  porcelain),  the  bases  and  dowels  may  be  cast  with  either  "B" 
or  "(\"  and  attached  to  the  saddles  with  the  84  or  76  solder. 

They  may  also  be  made  by  burnishing  34  g.  pure  gold  backings 
to  tlie  i^repared  porcelain  crowns,  fitting  and  soldering  dowels  made 
of  "Elastic"  gold,  to  the  backings  (or  boxes),  and  attaching  the 
completed  backings  to  the  saddles  with  84  or  76  solder. 


The  author  cannot  close  without  calling  attention  to  the  fact 
that  a  broad  conception  of  the  scientific  principles  involved  in  the 
chemical  and  physical  l^ehavior  of  the  various  materials  utiUzed 
in  connection  with  the  construction  of  prosthetic  restorations,  is 
a  most  potent  factor  toward  the  attainment  of  the  ideal. 

He  has  been  aided  materially  in  arriving  at  the  conclusions  pre- 
sented lierein  by  the  kindness  of  Mr.  H.  C.  Ney,  president  of  the 
J.  M.  Xey  (V)mj)any,  who  unstintingly  placed  at  the  author's 
(•(mimand  all  the  facilities  of  their  extensive  metallurgical  works 
in  Hartford. 

He  also  wishes  to  thank  Dr.  Peeso  particularly,  for  accepting 
this  eontribution  for  presentation  under  his  auspices. 


CHAPTER  XIX. 

THE  USES  AND  THE  VALUE  OF  RADIOGRAPHY 
IN  CROWN  AND  BRIDGE-WORK. 

By  FRED'K  K.  ream,  M.D.,  D.D.S., 

NEW   YORK    CITY, 
AND 

RICHARD  H.  RIETHMtTLLER,  Ph.D.,  D.D.S., 

NEW  YORK  CITY. 

The  first  question  that  interests  the  architect  or  the  construction 
engineer  is  the  nature  of  the  ground  upon  which  his  edifice  is  to 
rise,  and  no  effort  is  spared  to  ascertain  fully  the  character  of  the 
foundation  and  to  provide  by  every  available  means  its  stability, 
thereby  insuring  the  durability  and  safety  of  the  proposed  structure. 
It  is  upon  the  same  principles  that  the  successful  crown  and  bridge 
worker  calls  to  his  aid  all  the  means  available  for  ascertaining  the 
condition  of  the  tissues,  both  hard  and  soft,  before  laying  out  a 
detailed  plan  for  the  construction  of  the  prosthetic  appliance  to  be 
inserted  in  each  case.  This  precaution  not  only  spares  the  operator 
the  humiliation  of  failure,  the  loss  of  valuable  time  and  material, 
and  untold  annoyance,  but  it  also  protects  the  patient  against 
preA'entable  incon^Tnience,  and  safeguards  the  public's  faith  in  the 
efficiency  of  crown  and  bridge-work.  The  bridge  worker's  chief 
consideration,  however,  as  in  all  dental  operations,  no  matter  of 
how  apparently  trifling  a  nature,  must  be  the  patient's  health. 
Since  Dr.  William  Hunter,  of  London,  and  after  him  scores  of  others 
have  arraigned  the  dental  profession,  and  especially  the  crown  and 
bridge  worker,  for  causing  oral  sepsis  with  all  its  dire  sequelae  by 
their  disregard  of  the  physiologic  and  anatomic  bases  of  their 
work,  the  responsibilities  involved  in  any  intervention  in  the 
human  mouth  are  being  more  fully  realized  than  ever  before. 
The  spectre  of  "septic  dentistr}-"  has  alarmed  practitioners  and 
patients  alike,  especially  since  the  findings  of  such  investigators  as 
Billings,  Rosenow,  Flexner,  Mayo,  Grieves,  Hartzell,  and  others 
have  substantiated  Hunter's  timely  warnings. 

And  indeed,  no  other  dental   operation  is  more  conducive  to 


MKAXs  Foix'  i)i.\(;.\(>s[\(;  thk  fif.i.})  of  oi'Fuatios    400 

bringing  ahoiit  chronic  septic  conditions,  locally  as  Avell  as  systemat- 
ically, than  i)oorly  constrnctcd  crown  and  l)ridgc-\vork.  The  harm 
done  hy  suc-h  work  of  inferior  qnality  is  all  the  greater,  since  it  is 
often  not  recognized  nntil  far-reaching  damage  is  done  not  only  to 
the  teeth  and  the  month,  hnt  to  the  ])atient's  general  health.  A 
tooth  lost,  therefore,  may  he  i)referal)Ie  to  a  tooth  "entombed  in  a 
golden  casket." 

Means  for  Diagnosing  the  Field  of  Operation. — Before  the  discovery 
of  the  ,/-ra\  l)y  i'rofcssor  W.  K.  lii'intgen,  in  1895,  and  its  practical 
utilization  in  radiography,  a  well-developed  i)athological  sense,  an 
intimate  knowledge  of  general  and  special  dental  anatomy,  delicate 
palpation,  and  \ast  experience  were  the  only  means  for  diagnosing 
the  condition  of  the  hard  and  soft  tissues  of  the  jaws,  of  the  teeth 
in  general  and  the  abutments  in  special,  and  of  the  presence  of 
apparent  or  ob.scure  foci  of  infection;  but  it  is  self-evident  that 
these  diagnostic  agents  alone  ofl'ered  no  certain  guarantee  for  a 
correct  diagnosis  in  every  ca.se.  The  most  reliable  diagnostic  data 
are  furnished  by  the  radiograph,  this  reliability  standing  in  direct 
ratio  to  the  radiographer's  ability  in  making  exposures  and  interpret- 
ing the  resultant  picture.  A  poorly  taken  or  incorrectly  interjjreted 
radiograph  is  undoul)te(ll\'  almost  worse  than  none,  since  an  error 
in  technic  or  interi)retation  would  induce  the  bridge  worker  to 
proceed  with  his  operations  upon  false  premises.  l^Or  this  reason, 
the  modern  tendency  toward  specialization  seems  commendable. 
The  average  crown  and  bridge  worker  will  find  himself  too  busy 
to  devote  the  necessary  time  and  study  to  accjuiring  a  perfect 
technic  in  radiography.  On  the  other  hand,  his  coo])eration  with 
the  radiograj)her  is  indisj)ensable;  he  must  be  able  to  give  to  the 
specialist  intelligent  directions  as  to  the  special  features  he  wishes 
to  have  elucidated  in  each  case,  and  he  must  be  sufficiently  well 
versed  in  the  interpretation  of  pictures  to  recognize  the  j)athological 
or  anatomic  facts  disclosed  and  to  suggest,  if  necessar\',  a  rejK'tition 
of  the  radiographic  examination  under  altered  conditions  of  position, 
time  of  exposnre,  or  fpiality  of  rays  employed.  \\  lieu  such  intelli- 
gent coojM-ration  j)re\ails  l)etwe<'n  radiographer  and  bridge  worker, 
the  .r-ray  will  furnish  a  clear  insight  into  the  conditions  of  the  oral 
ti.ssues  invoked  in  a  crown  and  bridge  ojM'ration,  hence  ensure  the 
successful  accom[>lishmciit  of  the  |)roj)osed  o])eration;  it  will  ])rove 
an  invaluable  pro])hylactic  agent  against  failure  due  to  faulty 
diagnosis  and  a  most  imj)ortant  factor  toward  prosthetic  efficiency; 
it  will  a?<sure  the  patient  of  a  correct  interpretation  of  his  case,  the 


410 


RADIOGRAPHY  IN  CROWN  AND   BRIDGE-WORK 


best  possible  prosthetic  repair  of  his  dental  defects  and  adequate 
services  for  his  expenditures  in  time  and  money;  and  it  will  prevent 
oral  sepsis  with  all  its  grave  sequelae. 

Books  on  Dental  Radiography. — ^IVIanifestly,  it  cannot  be  the  pur- 
pose of  this  chapter  to  teach  dental  radiography  in  all  its  phases 
and  to  make  an  .r-ray  specialist  of  every  crown  and  bridge  worker. 
For  autodidactic  purposes,  we  recommend  such  books  as  Elementary 
and  Dental  Radiography,  by  H.  R.  Raper,  Dental  Radiology  by 
F.  L.  Satterlee,  and  a  perusal  of  the  numerous    articles  on  this 


Fig.  661 


subject  which  have  from  time  to  time  appeared  in  dental  magazine 
literature.  The  main  object  of  this  essay,  which  naturally  must 
have  a  limited  scope,  is  to  point  out  in  how  many  respects  radi- 
ography is  wonderfully  helpful,  in  fact  absolutely  indispensable  to 
the  crown  and  bridge  worker. 

Hints  Concerning  Outfit,  Technic,  Keeping  of  Records,  and  Interpre- 
tation.— It  cannot  be  our  purpose  to  mention  the  various  radiographic 
outfits  now  in  the  market,  or  to  compare  their  relative  merits  and 
fitness  for  our  special  work.     Suffice  it  to  say  that  the  radiographs 


IIIXTS  CnxCERNING  OUTFIT,  TECH  NIC,  ETC.  411 


Fig.  GG2 


Fifi  OG'i. — lAiOii  KlfiHR  (liaphniKin.  CJut-fjut  HUKKf;ste<l  by  Dr.  F.  K.  Ream,  and 
ijianiifantured  by  the  Scheidel  We.iU'rn  X-ray  foil  f 'o/iipaiiy  for  making  expoaunvs 
for  iii»i>er  and  lower  jawH.  The  out-fjut  providcM  the  pro|)('r  aiiuli;  for  tiiukiii>; 
exjjoHureM  in  the  iipijer  jaw,  hy  holding  it  directly  againHt  tlic  face.  (See  FIks.  004 
and  (V'tij). 


412         RADIOGRAPHY  IN  CROWN  AND  BRIDGE-M'ORK 


\ 


Fio.  6fi4 


Fig.  OB.j 


Fig.  666  — Lead  box  for  protecting  unexposed  films.     (Courtesy  of  American 
X-ray  Equipment  Company.) 


lUXTS  COXCKRMXG  OUTFIT,   TEVILMC,   ETC. 


4i:5 


shown  in  these  pages  ha\e  been  made  exchisi\el\"  with  a  Scheidel 
Western  X-ray  Coil  Company  outfit  as  shown  in  Figs.  661  and  662, 
which  has  given  entire  satisfaction.  As  an  accessory  to  this  outfit, 
the  cut-out  led  gUiss  diaphragm,  suggested  by  l\eam  and  ilhistrated 


I'k..   (i(i7.      I'ortaljlc  rlark-rooiri   box   for  dcvflopiiig  films.      (Couitcs^-  of   Ainciiciii 
X-ray  Equipinoiit  C'ompany.) 


ill  l''ig.  fi6:!,  Il;^^  proNrd  of  gir;it  liclj)  in  making  cxp<»snres  in  the 
upper  ;in(l  Ntwcc  j;i\\s.  'i'liis  cut-out  proxides  the  proper  angle 
for  making  cNiJosnres  in  tlie  upper  jaw  by  holding  it  directly  agaitist 
the  face,  as  shown  in  I''igs.  661  and  6('>.").     An  a|)pliance  for  holding 


414 


RADIOGRAPHY  IN  CROWN  AND   BRIDGE-WORK 


the  patient's  head  at  rest  during  exposures  of  longer  duration  is 
depicted  in  Fig.  676.  To  protect  unexposed  fihns  or  plates  against 
untoward  action  of  the  a:-rays,  they  are  kept  in  a  led  box  of  a  design 


Fig.  668. — Frosted  white  and  ruby  lamp  for  developing  and  reading  films  respectively. 
(Courtesy  of  American  X-ray  Equipment  Company.) 


Oatk 


F.   K     Rl\«.'««     M    !    ,  Ci    V 


:.F  TEETH 


)EWT.ii     R'i.DiOGhPF 


Fig.  669 


IIIXTS  COXCERXrXG  OUTFIT,  TECHXIC,   ETC.  415 

illustrated  in  Fig.  666.  The  development  of  exposed  films  or  plates 
is  made  according  to  the  well-known  chemical  principles  and 
routine  practice  adopted  in  photograph}'.  Since  usually,  develop- 
ment of  plates  or  films  immediately  or  soon  after  exposure  is  desired, 
both  operator  and  patient  being  anxious  to  arrive  at  a  definite 
diagnosis,  the  portable  dark-room  box  for  photographic  develop- 
ment shown  in  Fig.  ()()7  will  prove  a  valuable  accessory  which  can 


I'll..  070. — Position  for  making  exposures  of  cuspid  and  lalcral.      Patient  hdidin}, 

film  in  mr)utli. 


be  handled  either  by  the  radiographer  himself  or  by  his  assistant 
after  some  training,  as  a  substitute  for  a  special  dark-room.  This 
portable  dark-room  box  docs  away  with  the  necessity  of  setting  a 
room  or  j^art  thereof  asid<'  as  a  (hiik-ronni,  and  is  practical  in  c\-ery 
respect.  For  <levelo])ing,  if  a  dark-room  is  available,  or  for  "read- 
ing" the  devel(jped  film  or  plate  either  while  it  is  still  wet  or  after 
drying,  a  combination  frosted  white  and  ruby  lanij),  as  shown  in 
Fig.  ()(i<S,  is  useful.     A  holder  in  card  form  of  a  diaj)hanous  material 


416         RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

resembling  celluloid,  or,  better  still  of  black  cardboard  (see  Fig. 
669),  on  which  the  patient's  name,  the  date  of  exposure  and  the  case 
number  is  A\Titten,  serves  as  a  holder  for  the  developed  film,  and 


Fig.  C)71. — Position  for  taking  upper  right  teeth,  posterior  to  cuspid. 

permits  of  convenient  liandling,  interpreting,  and  filing  of  the  case 
for  ready  reference.  It  will  usually  be  found  that  the  negative 
presents  finer  details  than  a  print  made  therefrom,  the  more 
delicate  shades  often  being  lost  in  prints. 


IIIXTS  COXCERMXG  OUTFIT,  TECHNIC,  ETC.  417 

In  order  to  obtain  a  comprehensive  view  of  the  field  of  operation 
in  all  its  details,  and  to  arrive  at  definite  conchisions  concerning 
the  patient's  dental  condition  and  the  operative  measures  dictated 
thereby,  it  is  preferable,  in  fact  most  desirable  that,  instead  of 
securing  a  rontgenogram  of  only  two  or  three  teeth,  a  complete 
series  of  exposures  be  made,  thus  ensuring  a  complete  vision  of 


Ik..  <i12. — Ponitiidi  for  takiiiu  four  upper  aiiU-riur  U'otli.     Patient  i.s  liuldiug 
film  in  mouth  by  closing  teeth. 

tlic  fi<'ld  Jiiifl  a  strategic  map,  as  it  were,  by  win'cli  tlic  operative 
])ni<<'<liir(s  will   be  guided. 

Ill  making  exposures,  tlie  patient's  cooperation  must  be  solicited 
for  holding  tin'  film  in  its  proper  position  in  sudi  cases  as  are  shown 
in  P'igs.  070,  ()71,  and  074.  The  patient's  posture,  the  position  of 
the  apparatus  and  tube,  and  the  maimer  in  which  the  patient 
should  hold  the  film  in  the  mouth  when  making  exposures  of  the 
upper  lateral  and  cuspid  are  illustrated  in  Figs.  070.  For  taking 
u  radiograph  of  right  upper  teeth  ])osterior  to  the  cuspid,  the 
27 


418  RADIOGRAPHY  IN  CROWN  AND   BRIDGE-WORK 

various  units  are  arranged  in  the  positions  shown  in  Fig.  (371. 
Closing  of  the  teeth  for  holding  the  film  in  place  is  resorted  to  in 
making  an  exposure  of  the  upper  four  anterior  teeth,  as  shown  in 
Fig.  672.  In  similar  manner,  a  large  film  is  placed  across  the 
teeth  and  held  in  position  by  the  patient's  closed  mouth  in  exposures 
of  the  lower  anterior  teeth  (see  Fig.  673).     In  taking  radiographs 


Fig.    673. — Position    for  taking  exposures  of   lower  anterior  teeth.     Large   film    is 
placed  directly  across  the  teeth,  patient  closing  mouth  and  holding  film  in  position. 

of  lower  teeth  posterior  to  the  first  bicuspid,  the  arrangement  of 
the  units  is  made  as  shown  in  Fig.  674,  the  patient  holding  the  film 
in  place  with  his  finger.  P'or  obtaining  radiographs  of  impacted 
third  molars,  the  patient's  posture  must  be  given  especially  careful 
consideration.  In  such  cases,  the  use  of  large  plates  and  trans- 
illumination of  the  whole  thickness  of  the  head  becomes  necessary, 
as  is  shown  in  Fig.  675,  where  the  patient  is  being  examined  for 


iiixrs  coxcKhMxc;  outfit,  techmc,  etc. 


419 


impacted  lowei  third  molars.  In  exposures  of  the  maxillary  sinus, 
wliere  a  longer  exposure  is  needed,  the  head  is  held  in  position  on 
the  plate  by  a  head  clamp  as  shown  in  Fig.  07().  The  ray  must  be 
delivered  directly  on  a  line  with  the  orbits,  the  edge  of  the  cone 
to  rest  at  the  auditor}-  canal.  The  anterojxKsterior  position  for 
making  maxillary  simis  exi)osures,  and  the  manner  of  holding  the 


I  II..  f.ri.-    I'.j.-,itioii  U,t  takiii«  i-\\,uMm-  ol  trclh  |)(j.-i.Ti(,r  I..  l<nviT  lir.st  liicii.spid. 

head  firmly  in  position  on  the  plate  by  means  of  the  head  clainji 
are  demonstrated  in  Fig.  (i77.  As  an  aid  in  .securing  the  proper 
position  of  the  head  in  maxillary  sinus  c\i)osures,  the  angle  recom- 
mendefl  by  Dr.  F.  .M.  I.aw.  of  .\eu  V(»rk  (see  Fig.  (i7N),  can  !)(« 
employed  to  great  arlvantag*'. 

A.side  from  the  position  of  the  patient's  head,  ihc  arrangement  of 
the  various  units  of  the  apparafn>,  the  angle  of  incidence  of  the 


420 


RADIOGRAPHY  IN  CROWN  AND   BRIDGE-WORK 


ray,  etc.,  the  time  of  exposure  and  the  employment  of  a  "hard"  or 
"soft"  tube  are  of  great  importance.  These  latter  factors  are 
determined  by  the  nature  of  the  tissues  to  be  examined  and  the 


Fig.  675. — Position  for  taking  impacted  lower  third  molars. 


diagnostic  purpose  of  the  radiograph,  and  their  correct  application 
and  blending  with  the  former  factors  are  a  matter  of  judgment  and 
experience  and  constitute  the  chief  elements  of  the  radiographer's 
art.     Thus  it  becomes  apparent  that  the  successful  radiographer 


HIXTS  CONCERNING  OUTFIT,  TECHNIC,  ETC.  421 

must  c()iiil)iiu'  an  iutiinatc  knowledge  of  tlie  anatomy,  i)li\siology 
and  pathology  of  the  field  to  l)e  examined  with  a  complete  mastery 


Fr<;.  '170.  — I'ositioti  for  taking  oxpomire  of  riuixillary  .sinus,  showiiiu  ln-ad  clamp 
and  ijlal4;  in  jx^Hitiori.  Tlie  ray  must  ho  fliroftly  i>u  a  line  with  tlic  orbits,  and  edge 
of  cone  at  auditory  canal. 

of  tlie  |jriiieij)les  of  optics,  electricity  and  radiopliotograi)hy,  this 
cornhinatioii  Ix-ing  of  a  complex  eiiongh  nature  to  warrant 
specialization. 


422  RADIOGRAPHY  IN   CROWN  AND   BRIDGE-WORK 

In  the  interpretation  of  radiographs,  the  questions  of  perspective, 
of  distortions  and  of  the  appearance  of  ^'arions  kinds  and  conditions 
of  tissues  in  their  normal  and  pathological  states  play  an  important 


Fig.  G77. — Anteroposterior  position  for  making:  maxillary  sinus  exposures.     Head 
clamp  is  in  position  holding  head  firmly. 


I)AX(;ki{s  of  Till':  x  hwv 


423 


l)art.  The  best  diagnostic  results,  no  doubt,  are  obtained  from 
well-developed  dense  negatives  which  are  best  "read"  by  holding 
them  up  against  a  frosted  electric  light  bulb,  as  seen  in  Fig.  ()()8,  or  by 
laying  them  against  the  frosted  glass  plate  of  an  illuminated  shadow 
box.  In  thin  films  or  plates  which  are  so  often  seen,  a  great  amount 
of  valuable  detail  is  lost,  in  fact,  the  diagnostic  value  of  poor  radio- 
graphs is  worse  than  nil,  as  an  entirely  fault\'  diagnosis  may  result. 


Fii:.  (i7K. — Aimlc  used  and  rcioniiiiciiilcd  l).\   Dr.  1'.  M.  J.:i\v,  New  York,  Inr  nht.iiniiii 
proper  imsilion  in  ninkint;  maxillary  sinus  pxixisiiics. 


Dangers  of  the  X-ray  to  Operator  and  Patient.  Before  proceeding 
to  th<'  discussion  of  the  practical  apphcation  of  ra(liograi)hy  in 
crown  and  bridge  work,  a  word  of  warning  should  be  sounded 
against  careless  exposure  of  operator  and  patient  to  the  action  of 
the  ./-ray.  Before  this  action  was  fully  understood,  many  cases 
of  dcfiiiatitis,   cancer,   stcrilitx ,   insanity,   abortion,   leukemia,   and 


424  RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

alopecia  were  reported,  and  the  pioneer  workers  in  this  field  have 
dearly  paid  the  penalty  for  the  ignorance  that  long  prevailed  in 
regard  to  the  noxious  influences  of  the  .r-ray  upon  the  human 
tissues.  The  lamentable  fate  of  these  martyrs  of  science  should 
render  every  operator  who  enters  the  field  of  radiography  doubly 
cautious,  so  as  to  safeguard  his  patients'  and  his  own  health,  even 
life.  A  very  timely  warning  in  this  direction  has  been  sounded  by 
George  M.  Mackee,  M.D.,  of  New  York  City,  who  in  an  article 
entitled  "Radiodermatitis  following  X-ray  Examination  of  the 
Teeth,"  published  in  the  April,  1916,  issue  of  The  Dental  Cosmos, 
says,  "  The  operator  should  realize,  that  in  the  a*-ray  we  have  a  very 
powerful  and  dangerous  as  well  as  useful  agent;  and  in  order  to 
avoid  injury  to  himself  and  the  patient,  he  must  be  acquainted 
with  the  physics  and  the  biologic  effects  of  the  .r-ray,"  and  he  justly 
protests  "against  anything  but  the  most  scientific  rontgenology," 
and  he  urges  this  "not  only  in  order  to  assure  the  future  of  rontgen- 
ology, but  for  the  legal  protection  of  the  operator  as  well  as  the 
physical  welfare  of  the  subject." 


INDICATIONS  FOR   THE  USE   OF   RONTGENO GRAMS   IN 
CROWN   AND   BRIDGE-WORK. 

Coming  now  to  individual  cases  of  crown  and  bridge-work  in  which 
x-ray  examination  is  not  only  desirable,  but  imperative,  it  is  self- 
evident  that  the  broad  basis  upon  which  a  prosthetic  restoration 
is  to  be  placed  must  be  of  healthy  condition,  if  success  of  the  opera- 
tion is  to  be  insured.  In  a  great  many  cases  there  may  have 
been  going  on  a  slow  progressive  destruction  of  alveolar  process 
in  its  entiret}'  or  at  its  borders,  though  the  patient  was  not  aware 
thereof,  and  purely  ocular  or  digital  examination  may  have  revealed 
no  extraordinary  condition. 

Root  Resorption. — Owing  to  the  presence  of  irritation  of  some 
form  or  other,  the  apical  or  any  other  portion  of  one  or  several 
roots  which  are  to  be  employed  as  abutments,  may  have  been 
undergoing  slow  resorption,  thus  rendering  the  employment  of  such 
roots  of  extremely  dubious  value  as  pillars  for  reconstructions, 
unless  the  condition  is  duly  recognized  and,  if  possible,  such 
therapeutic  or  surgical  procedures  have  been  instituted  as  to  restore 
a  healthy  condition.  The  revelations  furnished  by  careful  a:-ray 
examination  of  such  cases  are  illustrated  in  Figs.  679,  680,  and  681. 


IXDICATIONS  FOR  THE  USE  OF  RONTGENOGRAMS      425 

Obscure    Dental    Caries    and    Pulp    Exposure.-  'I1i(>    presence    of 
caries  in  a  tooth  which  is  to  l)e  employed  as  an  al)utinent  is  not 


Fig.  679.  —  Resorption  of  root  ends 
and  alveolar  border  in  seeoiul  bicuspid 
and  first  molar.  .VIso  unfilled  canals 
and  iniptM-fect  fining  in  first  and  second 
molars. 


I"iG.  680.  —  Destruction  of  alveolar 
sui)port  of  crowned  tooth  that  ai)par- 
cntly  was  in  healthy  condition.  This 
Ijictiu'e  indicates  the  necessity  for  ;r-ray 
examination. 


I-"i(;.  (isi. — Complete  ab.sorption  of  mesial  root  of  lower  first  molar. 

always  reacHly  revealed  by  the  usual  methods  of  examination,  and 
even  if  detected  by  the.se  means,  the  (le,structi\'e  process  with  its 
concomitant  irritation  of  the  pulp  culminating  in  the  exposure  of 


Fig.  082. — Extensive  carie.s  and 
pulp  exi>o.sure  on  the  liiiKua!  surface 
of  lower  first  molar. 


Fro.  V)Ki. —  Unfilled  root  canals,  ab- 
.soe8.scd  roots,  and  obs(aire  caries  in  third 
molar.     Tj'iiKual  bar  on  .second  bicuspid. 


this  organ  may  have  rendctcd  llic  proposed  ;d)Mtiii(  iil   (ootli  unfit 
for  a  stable  restoration. 


420 


kAdiograpiiy  in  crown  And  HRibaE-woRK 


The  .T-ray  will  readily  reveal  the  presence  and  extent  of  such 
pathological  conditions,  and  prevent  error  in  judgment  and  failure 
of  the  reconstruction.  Cases  of  this  nature  are  shown  in  Figs. 
682  and  683. 

Necrosis. — The  detection  of  rarefied  or  necrotic  areas  in  any 
portion  of  the  maxillae,  and  especially  around  teeth  or  roots  to  be 
employed  as  crown  or  bridge  supports  cannot  but  be  of  vital  impor- 
tance both  to  the  patient  and  the  operator.  A  pathologic  condition 
of  this  nature,  if  overlooked,  would  not  only  seriously  impair  the 
value  of  any  restoration,  but  indeed  greatly  endanger  the  patient's 


Fig.  GS4. — Necrotic  area  in  the  region 
of  molar  roots  and  alveolar  abfscess. 


Fio.  685. — Rarefied  and  necrotic  areas 
around  roots  of  bridge  supports. 


Fic.  686. — Necrotic  area  around  the  first  molar  and  wires  placed  in  roots  for  purpose 

of  radiography. 


health  by  imbuing  him  with  a  false  sense  of  security.     Figs.  684 
to  686  are  ty])es  of  conditions  of  this  description. 

Impactions :  Retained,  Unerupted  or  Imperfectly  Formed  Teeth. — Of 
all  teeth,  the  third  molar  is  most  often  subject  to  anomalies  in 
shape  and  position,  and  its  utilization  as  a  crown  or  bridge  support 
therefore  largely  depends  upon  a  recognition  of  its  condition  in 
each  case.  Impactions,  as  illustrated  in  Figs.  687  to  692  demand 
timely  detection  and  prompt  attention,  even  if  the  teeth  thus 
affected  play  no  part  in  the  operative  restorative  plans,  as  they 
may  in  time  seriously  interfere  with  the  efficiency  of  the  restoration, 


I.\I)/(.\TI()\S  Foil'  THK    r.sVs   OF   h'dXFdFXOC  h\\  MS       42? 

aiul  may  lead  to  coinijlications  which  would  justly  he  hlauied  upon 
the  operator's  lack  of  circumspection.  The  pus  areas  so  frequently 
foimd  in  connection  with  impacted  teeth  may  spread  to  adjoininji 
teeth,  and  thus  hecome  a  grave  danger  to  such  teeth,  also  a  prolific 
source  of  svstemic  infection. 


Fig.    687. — Impacted     lower     third 


Fig.  088. — Impacted  third  molar,  with 


molar.   Owing  to  the  age  of  this  patient  pus  area  around  distal  surface  of  crown. 

and   density   of    bony    wall,    detail   is  \>ry  prolific  source  of  systemic  infection. 

lacking. 


Fu;.  (ix'.K — Impacted  low  •!   i  huil  niohn-.        Fig.  690.  —  Lower    third    molar    coni- 
.Absce.ssed  and  unfilled  root  canals  of  first  pletely  iml)cdded  in  the  luaiidiMe. 

permanent  molar. 


I'"lo.  (>'.»!        Itii|.:ictcd  first  bicuspid.  1"ig.  602.— Transversely  impacted  lower 

tliird  molar  and  cyst. 


Ketaitied  <l<'ciduous  teeth  or  unerupteil  |)ermaiieiit  teeth,  unless 
detected  heh»re  the  iiistitiition  of  restoniti\'e  measures,  may 
well  destro\  the  most  heaiitiful  reslorat ion,  since  the  unfitness  of 
a  deeidnou^   tooth    for  an    ahntment  or    the   delayed    eruption  of  a 


428 


RADIOGRAPHY  IN  CROWN  AND   BRIDGE-WORK 


permanent  tooth  will  necessitate  the  removal  and  possibly  recon- 
struction of  bridge-work.  Examples  of  anomalies  of  this  character 
are  illustrated  in  Figs.  093  to  696. 


Fig.  693. — Unerupted  upper  ouspid. 


Fig.  694. — Unerupted  and  imbedded 
lower  third  molar  in  the  mouth  of  a 
patient,  aged  sixty-five  years,  which 
gave  rise  to  great  suffering.  The  pa- 
tient was  almost  insane  from  pain  for 
a  period  of  three  years.  Pressure  on 
the  inferior  dental  nerve  together  with  a 
pulp  exposure  was  the  source  of  intense 
agony.  Owing  to  the  age  of  the  patient, 
calcification  was  almost  complete,  mak- 
ing the  surgical  removal  of  this  tooth 
extremely  difficult.  The  patient  made 
a  good  recovery  after  the  operation. 


Fig.  695. — Erupting  permanent 
bicuspid  beneath  crown  of  deciduous 
tooth. 


Fig.  696. — Interlocking  of  unerupted 
permanent  bicuspid  imbedded  in  crown 
of  deciduous  molar.  Also  root  of  per- 
manent first  molar. 


Abscess. — The  word  "abscess"  has  surely  become  the  bugbear  of 
the  dental  profession,  and  to  no  specialist  in  dentistry  has  the  pres- 
ence of  this  enemy  become  more  awe-inspiring  than  to  the  crown 
and  bridge  worker.  If  indicated  by  discoloration  of  the  crown  of 
the  tooth,  or  by  a  draining  fistula,  the  unsound  state  of  a  tooth 
and  its  bony  support  is  plainly  enough  indicated;  but  what  of 
the  innumerable  teeth  with  blind  foci  of  infection,  which  give  no 
evidence  of  their  presence  for  years,  and  only  after  a  more  or  less 
prolonged  period  of  obscure  activity  manifest  their  noxious  influence 


IXDICATIONS  FOR  THE  USE  OF  RONTGENOGRAMS       429 

ill  a  remote  systemic  condition?     The  utilization  of  such  a  tooth 
in  croAvn  and  bridge-work  naturally  subjects  the  patient  to  untold 


Fig.  (iU7. — Alvfolar  alwwss  in  latoriil,  cuspid, 
aud  Hr.st  bicuspid. 


Via.  698. — Abscess  of  loft  lateral 
incisor,  and  imperfect  root  canal 
fillings. 


Via.  099. — Badly  abscessed  root  of 
Irjwer  second  bicuspid  and  incipient 
abscess  of  molar. 


Fiu.  700. — Abscess  at  apex  of  first 
bicuspid. 


Fio.  701.      Abh'C'..-- of  lower    (ir>l    and 
second  bicuspids. 


Fi(i.  702. — First  and  second  molars 
l)adl,v  abscessed  and  decayed  roots  in- 
flicatinn  unfitness  for  crown  or  bridKC- 
\vr)rk. 


risk.s,  and  the  crown  and  bridKc  worker  has  practically  no  other, 
or  at  least  no  su<li  convenient  and  reliable  diagnostic  agent  at  his 


430         RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

command  for  the  detection  of  these  foci,  as  the  .r-ray.  Hence  it 
becomes  his  duty  to  ascertain  the  true  condition  of  the  teeth  and 
their  substructures  not  only  in  suspected  cases,  but  practically  in 
all  cases  where  restoration  is  demanded,  because  none  of  these 
cases  can  any  longer  be  considered  normal.  If  precautions  of  this 
nature  had  been  resorted  to  as  soon  as  the  .r-ray  became  available, 
the  crown  and  bridge  worker  could  have  spared  himself  the  recent 
arraignment  of  the  medical  and  dental  professions  at  large,  and  could 
Vave  a\'oided  the  jeopardy  in  which  the  very  principles  upon  which 
bis  specialty  is  based  have  been  temporarily  placed.  Even  when 
an  .r-ray  examination  is  made,  the  interpretation  of  the  residting 
rontgenogram  is  a  matter  of  greatest  importance,  because  the 
mistaken  incrimination  of  a  tooth  is  almost  as  serious  an  error  in 
judgment,  as  is  the  overlooking  and  neglect  of  such  a  condition  if 
present.  Rontgenograms  of  abscessed  conditions  probably  tax  the 
skill  in  technic  and  interpretation  of  the  radiologist  to  the  severest 
degree,  and  only  pictures  of  such  quality  as  shown  in  Figs.  G97  to 
702,  should  be  trusted  as  reliable  diagnostic  aids. 

Root-canal  Fillings. — While  the  determination  of  the  vitality  or 
non-vitality  of  a  tooth,  so  easily  accomplished  by  means  of  radiog- 
raphy, can  be  achieved  by  other  diagnostic  means,  the  utilization 
of  the  Rontgen  ray  in  root-canal  fillings  before,  during,  and  after 
this  operation  has  become  almost  a  sine  qua  non  of  dental  operative 
practice.  The  crown  and  bridge  worker,  of  course,  is  especially 
interested  in  the  ])rotection  of  roots  which  are  to  serve  as  supports 
for  his  work,  and  no  matter  whether  he  lea\'es  the  root  filling 
operation  to  some  other  operator,  or  does  it  himself,  he  could  not 
and  would  not  dispense  with  the  insurance  of  the  perfection  of 
root  fillings,  as  is  furnished  to  him  by  no  other  available  means 
than  the  .r-ray.  Like  obscure  chronic  dental  abscesses,  unfilled  Oi- 
imperfectly-filled  root  canals  are  a  prolific  source  of  systemic 
infection,  in  fact  a  large  percentage  of  chronic  blind  abscesses  are 
directly  caused  by  imperfect  root-canal  work,  the  infection  being 
set  up  by  the  hematogenous  route.  Various  stages  and  conditions 
of  root  canal  fillings  are  illustrated  in  Figs.  703  to  710. 

Perforations  (see  Figs.  707  to  713),  accidentally  produced  in  efforts 
at  enlarging  or  opening  root  canals  especially  in  cases  of  extensive 
calcification  or  formation  of  secondary  dentin,  or  the  presence  of 
foreign  bodies  such  as  fragments  of  broaches,  reamers,  burs,  etc.,  in 
root  canals  or  in  the  periapical  space,  cannot  escape  detection  if  the 
safet^'  measure  of  .r-ra^'  examination  is  resorted  to  before  instituting 


IXDICATIOXS  FOR  THE   USE  OF  RONTGENOGRAMS       431 

restorations,  and  the  necessity  of  such  timely  detection  will  surely 
not  be  challeuijed   l)\'   any   operator. 


Fig.  703. — Successful  effort  in  open- 
ing two  very  small  canals  to  the  apex 
in  upper  second  liicuspid. 


Fi(i.  704. — Successful  filling  oi  canals. 


I'lc.  705. — Imperfect  root  ca,nal  fill- 
ings, alveolar  abscesse.s  and  root  re- 
maining in  jaw. 


Fig.  706. — Filling  of  root  canals  and 
accidental  crowding  of  filling  material 
through  ai)ex.  This  ai)parently  wis 
non-irritating  and  gave  the  patient  no 
trouble. 


Fk;.  707.— Succe.ssfui  opening  of  calci- 
fied canals  with  wire  inserted  to  apex. 
.M.so -iucccssful  opening  of  pulp  chamber 
giving  a  clear  field  of  vi.sion  U>  canals  .so 
essential  in  Hucce.ssful  root  canal  work. 
Menial  canal  successfully  filled. 


l'"ii;.  70^.— Perfect  root-canal  fillint 
and  perforation. 


Roots.     Fificf)irf'(l  lioot.s.     1  nder  the  .stress  ol'  mastication  or   as 
the  result  of  trauma,  the  root  of  a  tooth  may  have  l)cen   fractured. 


432         RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

Usually  the  presence  of  such  a  fracture  is  readily  detected  by  the 
patient,  but  for  the  operator  it  is  of  great  value  to  determine  the 


Fig.  709. — Overfilled  and  perfor- 
ated roots,  unfilled  root,  abscess  and 
root  absorption. 


Fig.  710. — Three  perfect,  one  imperfect 
root-canal  fillings. 


Fig.  711. — First  molar  showing  perfor- 
ated root  with  futile  effort  to  fill  canal. 
Wires  inside  second  molar  showing  com- 
plete opening  to  apex. 


Fig.  712. — Root  perforation. 


Fig.  713. — Shows  broaches  placed  in  perforations  in  floor  of  pulp  chamber,  mis- 
taken for  canals  by  the  operator.  These  perforations  were  sealed  after  being  located 
by  broaches  and  tooth  filled. 


extent  and  nature  of  such  a  fracture,  if  he  wishes  to  prevent  the 
loss  of  the  root  which  may  be  extremely  valuable  as  an  abutment 
(see  Fig.  714). 


INDICATIONS  FOR   THE   USE  OF  RONTGENOGRAMS     433 

Measuring  Roofs. — -The  length  of  the  roots  of  teeth  to  be  employed 
as  abutments,  especially  if  a  post  is  to  be  inserted  in  the  root  canal, 
can  be  readily  determined  by  a  correctly-posed  rontgenograph. 
An  accurate  knowledge  of  this  important  datum  naturally  greatly 


Fig.  714.  —  Shows  frac- 
tured root  of  central  incisor, 
result  of  traumatism. 


Fig.  715. — Demonstrating  the  plan  of  introduc- 
ing wires  in  canals  of  lower  teeth  and  the  correct 
position  for  making  exposure. 


Fig.  716. — Abscess  of 
l<jwer  centrals,  the  cor- 
rect position  and  possi- 
bility of  showing  normal 
longth  of  lower  teeth, 
and  lack  of  root-canal 
filling'. 


Fig.  717. — ^Wires  inserted  in 
root  canals  for  measuring  pur- 
poses. 


Fig.  718.— Wire  in- 
serted in  root  canal  for 
purposes  of  diagnosis. 


facihtates  the  operator's  task  in  determining  Jiot  only  the  length 
of  tlie  po.st  which  he  may  insert,  but  also  the  limit  of  stress  and 
strain  which  lie  may  impose  upon  a  particular  abutment.  The 
method  of  taking  accurate  measurement  of  the  length  of  a  root,  by 
means  of  wires  inserted  therein,  is  illustrated  in  Figs.  715  to  718. 
2S 


434 


RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 


Anomalies  in  the  Number  of  Roots. — Although  he  be  thoroughly 
familiar  with  special  dental  anatomy,  the  crown  and  bridge  worker 
may  be  uncertain  as  to  the  number  of  roots  present  in  a  particular 
tooth,  since  deviations  from  the  normal  number  of  roots  are  met 
with  quite  frequently.  Failure  to  detect  the  presence  of  such  an 
anomaly  in  a  patient  would  naturally  lead,  sooner  or  later,  to 
complications,  the  nature  of  which  would  remain  obscure  to  the 
patient  as  well  as  the  operator,  were '  it  not  for  radiographic 
evidence  (see  Figs.  719  and  720). 


Fig.  719. — Lower  double-rooted 
cuspid,  showing  the  possibility  of 
failure  by  following  the  usual  rule 
of  looking  for  one  canal  in  anterior 
teeth.  Such  multiple  canals  are 
often  seen  by  the  radiographer. 


Fig.  720. 


-Lower  first  molar  with  three 
root  canals. 


Anomalies  in  the  Shape  and  Direction  of  Roots. — Curved,  crooked, 
constricted  or  flattened  roots  present  special  difficulties  to  the 
crown  and  bridge  worker.  The  torsion  of  a  root  may  even  be  so 
pronounced  as  to  entirely  preclude  the  possibility  of  successful  root- 
canal  filling,  and  it  would  be  nothing  short  of  folly  to  attempt  the 
placement  of  a  restoration  upon  such  an  unreliable  foundation. 
The  general  direction  of  roots  and  their  parallelism,  so  important 
in  bridge  restorations,  is  quickly  determined  by  radiographs,  as 
shown  in  Figs.  721  and  722. 

Proximity  of  Roots  to  the  Maxillary  Sinns.—1\\e  proximity  of 
roots  to  the  maxillary  sinus  may  be  a  factor  in  determining  what 
amount  of  stress  may  be  safely  imposed  upon  an  abutment.  In 
case  of  protrusion  of  a  root  into  the  sinus  itself,  it  is,  of  course, 
essential  that  the  operator  be  aware  of  this  fortunately  rare  con- 
dition, and  be  guided  accordingly  in  his  operative  procedures  (see 
Figs.  723  and  724).     Disease  of  the  maxillary  sinus,  if  suspected. 


IXDICATIOXS  FOR  THE   USE  OF  RONTGENOGRAMS      435 

shoiikl  be  fully  ascertained  before  any  steps  are  taken  toward 
crown  or  bridge  restoration,  since  the  pathok^gical  condition  could 
only  be  seriously  aggravated  by  untimely  and  ill-advised  prosthetic 
interference. 


Fig.  721.  —  Crooked  root  of  lower 
.•second  bicuspid  demonstrating  the  im- 
possilnlitj'  of  successful  root  filling. 
First  molar  shows  enlarged  tooth  roots 
with  calcified  canals. 


Fn;.  722. — Crooked  roots  of  a  lower 
second  molar  with  alveolar  border  de- 
stroj-ed  by  pj-orrhea. 


Root  Fmgtiients  Left  in  the  Mouth. — It  goes  without  saying  that 
the  presence  of  a  root  fragment  left  in  the  alveolar  process 
(see  Figs.  725  and  726)  would  seriously  jeopard  the  usefulness  and 
service  of  a  bridge,  since  an  acute  infection  ma\'  at  an>'  time  be 
.set  up  around  such  a  fragment  as  a  nucleus.  The  .r-ra\'  readily 
re\eals  tli(^  presence  of  any  such  fragments,  and  their   extraction 


Fit;.  72'-i. — Six  teeth  on  small  film  and 
position  for  making  exposure.  .\lve()lar 
iib«ces.s  and  unfilled  canal  of  .second  bi- 
cuspid. Large  area  above  molar.s  shows 
•lipping  down  of  lower  Ijorder  <>!  maxiUnn/ 
xinuK,  but  (loos  n<it  indicate  any  special 
p:ttho|r>gical  crmdition. 


l'"i<;.  724. — Upper  teeth,  abscesses 
and  unfilled  canals,  rarefied  area 
extending  from  lateral  to  first  molar. 
The  light  area  extending  over  bicus- 
))ifl  and  molar  is  the  anterinr  liorder 
of  the  maxillary  sin\is. 


becomes  a  inatt<'r  of  course  bcfon"  attemptiug  prosthesis,  since 
llic  removal  of  dcepl.x-  iuibcddf*!  I'oot  fragmeuts  from  under  a 
bri<lge  offers  uiiiieeessjiry  eom|)li(ii( ions,  mikI  miglil  result  in  flie 
(lestruetion  of  the  bridge  by  the  exodontist. 


436         RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

Pyorrhea    Alveolaris. — Next    to    dental    caries,    the    disease,    or 
rather,   the  complex   of  diseases   called  pyorrhea    alveolaris   calls 


Fig.  725. — Lateral  root  that  re- 
mained in  the  mouth  ten  years  after 
effort  at  extraction. 


Fig.  726. — Later  effort  which  re- 
sulted in  pushing  the  root  in  the  alveo- 
lar region  at  the  floor  of  the  nose. 


Fig.  727. — Portion  of  first  bicuspid  apex 
located  in  necrotic  area  in  immediate  proximity 
to  the  wall  of  the  maxillary  sinus. 


Fig.  728. — Pyorrheal  teeth  and 
normal  position  for  making  radio- 
graph of  lower  incisors. 


Fig.  729. — Pyorrheal  teeth,  and 
complete  destruction  of  alveolar 
support. 


Fig.  730. — Ill-fitting    crown    placed    over 
tooth  with  broken  broach  left  in  root  canal. 


IXDICATIOXS  FOR  THE  USE  OF  RONTGENOGRAMS      437 

most  frequently  for  prosthetic  restoration  of  the  masticating 
organs.  After  thorough  surgical  ciu-etmeut  and  therai)eutic  and 
dietetic  measures  have  been  instituted  by  the  pyorrhea  specialist, 
the  crown  and  bridge  worker  may  be  called  upon  to  afford  the 
patient's  teeth  surgical  rest  in  the  form  of  immobilization  b>'  means 
of  a  temporary  splint.  As  soon  as  consolidation  of  the  affected 
teeth  lias  taken  place,  his  plans  naturally  turn  to  permanent  restora- 
tion, the  jjracticability  of  which  is  again  determined  by  the  radio- 
graphic findings.  It  would  be  folly  to  base  any  reconstructional 
work  upon  weak  and  unreliable  abutments  which  are  supported 
by  but  a  doubtfully  strong,  worse  by  an  almost  completely  destroyed 
ah-eolus,  as  shown  in  Figs.  728  and  729.  The  radiograph  will 
be  the  final  criterion  as  to  the  retention  or  elimination  of  doubtful 
links  in  the  chain  of  abutments;  it  will  militate  against  unwise 
hyperconservatism,  and  safeguard  an  honest  prognosis. 


Fig.  7.31. — Steel  needle  broken  during  tuberositj-  injection. 

Foreign  Bodies. — Fortunately,  the  presence  of  foreign  bodies  in 
the  ma.xilla'  usually  manifests  itself  by  a  violent  reaction;  yet  in 
persons  of  low  vitality  whose  defensive  force  is  greatly  reduced,  a 
foreign  body  may  be  tolerated  by  the  tissues  for  a  surprisingly 
prolonged  period  of  time.  Broken  broaches,  })robes,  burs,  reamers, 
drills,  etc.,  may  remain  in  root  canals  without  signaling  their 
presence  by  inflammatory  reaction,  and  the  placement  of  a  crown 
over  such  a  tooth  may  cast  a  serious  reflexion  upon  the  crown 
aiifl  bridge  worker's  circumspection  (.see  Fig.  730).  An  excessive 
amount  of  gutta-p<'rcha  or  resin  may  have  been  forced  through  the 
ajMcal  foramen  into  the  peria[)ical  space  in  an  attempt  to  fill  a  root 
canal  to  the  end,  and  tliougli  it  may  be  lying  dormant  for  awhile, 
it  will  surel\'  sometime  sooner  or  later  manifest  its  presence  by  a 
violent  inflammation.  Here  again,  the  .r-ray  discloses  the  location 
and  amount  ui  foreign  material  and  gnidcs  tlic  surgeon's  hands  in 
its  removal  by  way  (»f  ahcolotomy. 


438         RADIOGRAPHY  IN  CROWN  AND   BRIDGE-WORK 

As  conductive  anesthesia  is  daily  growing  in  popularity,  and  since 
the  use  of  steel  needles,  despite  numerous  contra-indications,  is 
still  being  persisted  in  by  many  operators,  the  number  of  instances 
in  which  needles  are  fractured  within  the  tissues  is  bound  to  increase. 
If  sterile,  these  needles  may  cause  no  disturbance  whatever  for  some 
time,  yet  any  decrease  in  the  resistance  of  the  area  in  question 
may  lead  to  complications  which  may  prove  fatal  to  the  crown  and 
bridge  worker's  achievement.  Radiographic  search,  therefore,  for 
fractured  steel  needles  is  indicated  whenever  there  is  the  slightest 
suspicion  of  such  an  accident  having  occurred,  and  the  fragment  is 
to  be  removed  by  surgical  intervention.  A  case  of  this  description 
is  illustrated  in  Fig.  731. 

ILL-FITTING    CROWNS    AND   BRIDGES    AND    THEIR 
SEQUELS. 

After  what  has  already  been  said  about  the  untoward  sequelae  of 
ill-fitting  crowns  and  bridges,  it  seems  hardly  necessary  to  empha- 
size once  more  the  multiple  dangers  that  may  lurk  in  poorly  con- 
structed work  for  the  preservation  of  the  abutment  units  as  well  as 
the  oral  and  general  health  of  the  patient.  Since  the  question  has 
been  seriously  asked :  "Is  crown  and  bridge-work  a  menace?",  it 
behooves  the  specialist  to  justify  his  answer:  "Not,  if  constructed 
with  due  consideration  of  the  principles  of  mechanics,  anatomy, 
physiology  and  pathology  of  the  units  involved,"  by  a  judicious 
and  liberal  application  of  all  the  means  available  for  the  preclusion 
of  failure,  and  toward  this  end,  the  .r-ray  has  surely  proved  itself 
to  be  an  indispensable  adjuvant.  The  illustrations  presented  in 
Figs.  732  to  737  are  shocking  negative  examples  of  bridge-work, 
and  their  correct  interpretation  and  explanation  to  the  patient 
will  in  many  cases  result  in  the  patient's  realization  of  the  necessity 
of  the  elimination  of  the  pathologic  conditions  present  and  in  his 
consent  to  a  reconstruction  of  the  prosthetic  work  upon  truly 
scientific  principles  after  removal  of  the  old  menace  and  restoration 
of  the  tissues  to  full  health.  A  series  of  radiographs  encompassing 
the  full  upper  and  lower  arches  will  afford  the  best  survey  over  the 
condition  of  a  mouth.  A  striking  example  of  this  sort  is  furnished 
in  Figs.  738  to  745.  The  patient,  a  well-knoM^n  physician  and 
writer  on  general  and,  since  the  revelation  of  his  own  deplorable 
dental  condition,  oral  prophylaxis,  claimed  to  have  a  perfectly 
"comfortable"  mouth,   while  systemically  he  was  suffering  with 


ILL-FITTING  CROWNS  AND  BRIDGES 


439 


rheumatoid  arthritis  associated  with  septic  endocarditis.  A 
radiographic  examination  of  his  mouth  revealed  tiie  following 
conditions: 


Fig.  732. — Ill-fitting  bicuspid  orown. 
hyperrementosed  root,  and  alveolar 
abscess. 


Fig.  734.  —  Alveolar  abscess.  Two 
overhanging  dummies  on  bridge.  Ill- 
fitting  crown  on  bicuspid . 


Fig.  7.3.'^. — Lower  first  molar,  with 
both  roots  abscessed.  Anterior  root 
bathed  in  pus.  Extensive  destruction 
of  process.  Posterior  root  shows  caries 
under  crown. 


Fi(i.  7.3.5. — Large  abscess  sack  at  root 
of  bicuspid  imder  bridge,  and  ill-fitting 
crown. 


I'"i<;.    7.'iG. — ^Biou.s|>ifi    with    apical    abscess  Fig.  7.37. — Large  abscess  area  pro- 

and  ill-fitting  l)icuHpid  and  mf)lar  crowns.  <hiced  by  death  of  pulp  under  ill-fit- 

ting i)i(Mispid  ciowii. 


Fig.  738:  Claries  hcricath  filling;  alveolar  abscess  draining  into 
intcnlcntal  space;  absence  of  root  c-anal  fillings  in  fir.st,  second,  and 
thini  molars. 


440  RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

Fig.  739:]    Imperfect  root-canal  fillings  in  bicuspid  and   cuspid, 
with  calcification  of  unfillecj  portions;  poorly  fitting  band. 


Fig.  738 


Fig.  7;j9 


Fig.  740 


Fig.  741 


Fig.  742 


Fig.  743 


Fig.  744 


Fig.  745 


ILL-FITTIXG  CROWNS  AND   BRIDGES 


441 


Fig.  746 


Fio.  747 


Fi<;.  748 


Fig.  749 


Fir;.  750 


Fig.  751 


Fia.  752 


442  RADIOGRAPHY  IN  CROWN  AND  BRIDGE-WORK 

Fig.  740:   Crooked  third  molar  roots. 

Fig.  741 :   Similar  conditions  as  in  Figs.  738  to  740. 

Figs.  742  to  745:  General  septic  and  rarefied  areas  involving 
apices  of  roots;  syndrome  of  untoward  mechanical  and  pathologic 
conditions.  , 

Thorough  corrective  treatment,  beginning  with  the  removal  of 
the  "septic"  crown  and  bridge-work,  restitution  of  the  tissues  to 
health,  correct  root-canal  fillings  and  correctly  constructed  crown 
and  bridge-work  restored  the  patient  to  health,  the  systemic 
symptoms  subsiding  with  the  removal  of  the  oral  sepsis. 

Another  interesting  example  of  a  supposedly  healthy  mouth  is 
illustrated  in  Figs.  746  to  752.  This  patient  was  of  normal  appear- 
ance and  weight,  and  claimed  health  with  the  exception  of  rheu- 
matism and  slight  diabetes.  All  efforts  to  locate  the  seat  of  this 
trouble  proved  negative,  until  the  mouth  was  examined.  For 
the  sake  of  practice,  the  interpretation  of  this  radiographic  series 
is  left  to  the  reader.  In  this  case,  the  forceps  seem  to  be  indicated 
as  the  best  therapeutic  agent  for  the  restoration  of  the  patient's 
health. 

Conclusion. — In  conclusion,  it  may  not  be  amiss  to  point  out  the 
usefulness  of  which,  from  a  medico-legal  aspect,  may  be  the  .r-ray 
in  substantiating  or  disproving  charges  of  malpractice  brought 
against  the  crown  and  bridge  worker;  for  it  is  by  this  means  that 
the  success  of  attempts  at  palliative  treatment  prior  to  insertion  of 
bridge-work,  and  the  accuracy  of  bands,  the  paralielity  of  posts, 
the  perfection  of  root-canal  fillings,  in  short  almost  all  the  factors 
that  constitute  scientific  bridge-work  can  be  demonstrated  ad 
oculos.  In  teaching  crown  and  bridge  also,  the  radiograph  is  an 
instructive  and  convincing  aid  in  demonstrating  poor  versus  good 
bridge-work. 

In  fine,  dentistry  more  than  any  other  profession  has,  despite  the 
remarkably  short  period  of  time  in  which  it  has  evolved  from  a 
trade  into  an  art  and  science,  availed  itself  of  every  innovation  in 
the  fields  of  technic  and  science  in  its  arduous  strife  toward  perfec- 
tion. It  therefore  behooves  the  specialist  in  crown  and  bridge- 
work,  who  is  called  upon  to  make  the  most  skilful  restorations 
known  in  the  realm  of  prosthesis,  to  avail  himself  to  the  fullest 
extent  of  William  Konrad  Rohtgen's  discovery. 


INDEX 


Abscess,  dento-alveolar,  25 
acute,  treatment  of,  26 

aromatic  sulphuric  aciti  in,  27 
peroxide  of  hydrogen  in,  2() 
danger  of,  27 
chronic,  treatment  of,  30 
estabhshing  fistula  in,  28 
locating  apex  of  root  in,  28 
painless   insertion   of  hypodermic 

needle  in,  29 
r:idiogi-aphy  and,  428 
root  amputation  in,  31 
fiUing  canal  in,  31 
treatment  of  wound,  32 
Aljutments      for       extension      saddle 
bridges,  314 
inlay,  260.     See  Inlay  abutments, 
paralleling  of,  207 

Weinstein's  device  for,  208 
with  tube  in  mouth,  209 
posterior,  paralleling  of,  210 
preparatif)n  of,  207 
for  removable  bridges,  paralleling  of, 
228  _ 
retaining,  226,  227 
supporting,  22ii,  227 
sui)j)()rting,  272 

gold   fillings,   cavity  for,   prepara- 
tion of,  273 
finishing  of,  273 
imi)ression  for,  273 
indications  for,  272 
inlay,  274 

adjusting  of,  275 

casting  of,  27") 

(;avity  for,  pre|)aration  of,  274 

cementing  ui,  27.') 

completion  of  bri<lgi'  with  spur, 

274 
finishing  fjf,  27.j 
forming  seat  for  spur,  275 
location  <;f  po.sition  on  model  for 

st)ur,  274 
maKirig  of  spur,  274 
shai)ing  of  spur,  274 
waxing  of,  275 
Alloys,  binary,  360 


Alloys,   binary,   comparative  hardness 
of,  371 
melting  points  of,  368 
of  gold,  compounding  of,  383 

and    copper,    melting    points    of, 

364 
and  palladium,  melting  points  of, 

366 
and  platinum,   melting  jjoints  of, 

365 
and  silver,  melting  points  of,  362 
solders,  382 
for  making  bantls,  164 
new  series  of,  371 

application  of,  in  Peeso's  system 
of  crown  and  bridge-work,  405 
construction  of  bands  with,  405 
of  dummies  with,   407 
of  floors  with,  405 
of  inlay  abutments  with,  406 
of  inner  caps  with,  405 
of  outer  half  bands  with,  406 
of  saddles  with,  407 
of  telescope  crowns  with,  406 
melting  points  of,  405 
for  jjrosthetic  castings,  374 
Alveolar  abscess,  radiography  and,  428 
Amalgam,    building-up    broken    down 

roots  with,  143 
Ami)utation  of  root  ends,  31 
Anatomical  articulators,  133 
Anesthesia  in  devitalization  of  ])ulp,  41, 

44 
Anterior     crowns,      measurement      of 
stump  for,  187 
teeth,  l)anded  crowns  for,  187 
inlay  iibutments  for,  261 

attiu^hing  sy)rue  wire  in,  262 
building    inlay    in    wax    with 

tube  in  place,  262 
canal  for  enlarging  of,  261 
casting  of,  262 

cavity    of,    finishing    of,     for 
.s(!con(l  inlay,  264 
preparation   of,    for  second 

lay,  2()3 
.shaping  of,  261 
filling  |)ure  gold   m;itri\  with 
(!oin  gold,  266 


444 


INDEX 


Anterior  teeth,  inlay  abutments  for, 
finishing  of,  267 
fitting     tube     with     asbestos 

paper  in,  262 
flasking  of,  262 
impression  with  inlay  in  place, 

263 
investing  of,  266,  267 
model  for,  preparation  of,  263 
polishing  inlay  in,  267 
removal    of    tube    with    wax 

inlay  from  mandrel,  262 
second   inlay   in,   making   of, 

265 
soldering  with  bridge,  267 
waxing  of,  267 
jacket  crowns  for,  197 
lower,    radiography    of,    position 

for,  418 
porcelain  crowns  for,  302 
bite  in,  302 

casting    bases    on    abutment 
caps,  306 
on  small  saddles,  306 
copper  drills  in,  304 
crowns  in,  302 
impressions  in,  302 
retaining  wall  in,  304 
saddle  in,  adjusting  of,  302 
impression  for,  302 
making  of,  302 
shrinking  of  cast  base  on  cool- 
ing, 305 
tin  foil  in,  use  of,  305 
waxing    bases    to    abutment 
cap,  307 
to  saddle,  307 
posts  for,  307 
pulp  canals  of,  52 
removable  attachments  for,  251 
adjusting  band  in,  251 
broken  facings  in,  cause  of,  258 

prevention  of,  258 
enlarging  entrance  to  tube  in, 

254 
facing  roots  in,  252 
finishing  caps  in,  254 
fitting  band  in,  251 

split  pin  to  tube  and  floor 

of  outer  cap,  254 
tubes  in,  253 
investing  spht  pin  in  floor,  255 
making  half-band,  256 
soldering  half-band  to  floor, 
256 
split  pin  in  floor,  255 
tubes  in,  253 
sweating  floor  in,  252 
trimming  outer  floor  to  inner 
cap,  256 
upper,    radiography    of,    position 
for,  417 


Arsenic  in  devitalization  of  pulp,  38 
Articulating  plates,  138 

surfaces,  direction  of,  139 
Articulators,  133 
anatomical,  133 

with  face  bow,  134 
crown,  133 
plaster,  135 
making  of,  135 
Artificial  stone,  Weinstein's,  120 

impressions  with,  filling  of,  121 
preparation  of,  121 
separation  of,  122 
mixing  of,  121 
Autogenous  soldering,  159 


B 


Band,  sweating  of  floors  to,  189 

uniting  of  cusp  to,  185 
Banded  crowns  for  anterior  teeth,  187 
Bands,  construction  of,  new  series  of 
alloys  and,  405 
contouring  of,  178 
fitting  of,  to  anterior  crowns,  188 
to  roots  broken  below  gum  line, 
145 
decayed  below  gum  line,  145 
making  of,  alloys  suitable  for,  164 
lapped  joint  vs.  abutted  joint,  161 
technic  of,  162 
outer  half,  construction  of,  new  series 

of  alloys  and,  406 
in  removable  attachment  for  anterior 
teeth,  adjusting  of,  251 
fitting  of,  251 
shaping  of,  use  of   collar  pliers  in, 

175 
soldered  joint,  164 
sweating  of,  with  blow  pipe,  163 

with  Bunsen  flame,  163 
trimming  of  teeth  for,  82 
waxing  in  of,  in  impressions,  127 
Bicuspids,  jacket  crowns  for,  199 
lower,  cusps  of,  172 
pulp  canals  of,  52 
trimming  of,  96 
radiography  of,  position  for,  419 
upper,  first,  placing  pin  in,  190 
pulp  canals  of,  51 
trimming  of,  101 
Binary  alloys,  360 

comparative  hardness  of,  371 
melting  points  of,  368 
Bite  in  porcelain  crowns  for  anterior 
teeth,  302 
proper  closure  in,  securing  of,  125 
in  saddle  bridges  with  abutments  at 
both  ends,  335 
Bridge-work,  gold  for,  372 
object  of,  205 


INDEX 


445 


Bridges,  dental,  205 

abutments  for,  paralleling  of,  207 
Weinstein's  devise  for,  208 
with  tube  in  mouth,  209 
posterior,     paralleling     of,     on 

model,  210 
preparation  of,  207 
classification  of,  205 
extension,  220  I 

l)icuspids,  220 

rule  regarding  supports  for,  221 
small  anterior,  220 
with  saddles,  221 
fixed,  206,  215 

anterior,  backing  of,  218 
grinding  of,  218 
interchangeable   facings   and, 
finishing  of,  219 
grinding  duplicates,  220 
investing  for  soldering,  218 
cementing  of,  337 

bleeding  gums  and,  338 
cleansing  before,  337 
drying  field  of  operation  in, 
338 
out  roots  in,  338 
mixing  cement,  338 
placing  cement  in  canals,  338 
removal  of  excess  cement,  338 
common  type  of,  216 
cusps  for,  grinding  of,  217 

selecticm  of,  217 
facings  for,  backing  of,  21() 
grinding  of,  2  Hi 
selection  of,  216 
porcelain   crowns  with  soldered 
base  in,  221 
fitting  bases,  222 
grinding  of,  222 
investing  of,  223 
j)lacing  i)osts  in,  222 
soldering  jjosts  in,  222 
posterior,  investing  of,  217 

waxing-up  of,  217 
soldering  in  sections,  218 
large,  divided,  75 

one  piece,  75 
occluding  with  plate,  73 
occlusion  and,  21 1 
jKjrcelain,  151 
nmiovable,  200,  225 

abut  ments  for  i)arall(!ling  of,  228 
retaining,  22(1,  227 
su|)portirig,  226,  227 
advantages       of,       ov(t      fixeil 

bridges,  225 
for  anterior  tcetli,  251 
altaclitnenis  for,  226 
(;enienting  of,  339 
l)ridge  in  inoutli,  '.V-iU 
cleansing  bcrfore,  '■>'-'>U 
inluyH  for,  339 


Bridges,  dental,  removable,  cementing 
of  inlays  for,  cement 
syringe  in,  340 
cleansing  of,  340 
removal  of  excess  cement,  339 

of  wax,  339 
waxing  preparatory  to,  339 
inlay    abutments    in,    260.    See 

Inlay  abutments, 
key  and  shoe  attachment,  250. 

See  Key  and  shoe, 
porcelain  crown  with  cast  base, 

301.     See  Crown  porcelain, 
split  pins  for,  284 
telescope  crowns  in,  227 
value  of,  accuracy  and,  22() 
requisites  for,  206 
supports,  74 

tubes  for,  276.     See  Tubes. 
Bryant's  system  of  replacing  broken 
facings,  350 


Canals,  pulp.    See  Pulp  canals. 

Cap,  inner,  construction  of,  new  series 

of  alloys  and,  405 
Caps  trimming  of  teeth  for,  82 

waxing  in  of,  in  impressions,  127 
Caries,   dental,   radiography   and,   425 
Carmine  solution,  preparation  of,  123 
Casting,  fluxes  for,  400 

investment  compounds  for,  392 
formula  for,  396 
hot  or  cold  moulds  in,  394,  395 
process,    all    porcelain   crowns   with 
cast  base,  200 
grinding  of  crowns  in,  201 
root  preparation  in,  200 
selection  of  crowns  in,  201 
wax  base,  casting  of,  201 
flasking  of,  201 
availability  of,  in  crown  work,  199 
banded  crowns,  201 
casting  of,  202 
flasking  of,  202 
porcelain  facings,  202 
waxing  of,  202 
casting  flirectly  on  facings,  204 
drying  out  flask  in,  204 
facings    nsinovcid    and    cemented 

after  casting  is  made,  203 
heating  flask  in,  204 
Coastings,  iiflay,  gold  for,  375 
formula  for,  377 
prosthetic,  gol<l  for,  371 
(,'em(Mit  syringe,  340 
Ceiiicnting    lixed    bridgcis,    337.      jS'ee 
liridgcs,  fix('d,  ci'iiKMiting  of. 
ol  inlay  abutments  for  molars,  270 
for  removable  bridg(!S,  339 


446 


INDEX 


Cementing  of  removable  bridges,  339. 
See   Bridges,  removable,    cementing  \ 
of. 
Clasp  metals,  378 

composition  of,  379 
melting  point  of,  379  ! 

Clasp-wire  split  pins,  285 
Cleavers,  enamel,  118 
Cologne  solution,  preparation  of,  123 
Contouring  of  bands,  178 

pliers,  160 
Copper,  alloys  of,  melting  points  of,  363 
Crown  articulators,  133 

setter,  343 
Crowning  of  broken-down  roots,  143 
Crowns,  anterior,  fitting  bands  to,  188 
measurement  of  stump  for,  187 
banded,  for  anterior  teeth,  187 
casting  process  in,  201 
porcelain  facings,  casting  process 
in,  202 
casting  process  in,  availability  of,  199 
combination,  241  | 

construction  of,  241  j 

contraction  of  tubes  on  soldering, 

247 
countersinking  entrance  of  tube, 
247  ; 

,'  cusps  of,  adjusting  of,  248 

fitting  of,  248  | 

investing  of,  249  I 

preparation  of,  248 
selecting  of,  248  j 

soldering  of,  to  cap,  249  ■ 

enlarging  necks,  for  split  pins,  247 
fitting  split  pins  in  tubes,  247 

tube  in,  243 
impression  for,  242 
inner  cap  of,  making  of,  243 
investing  of,  244 
outer  cap  of,  making  of,  245 
soldering  split  pin  in  outer  cap,  248 
in  tube,  244 
cutting  band,  sweating,   and  fitting 

band  to  stump,  174 
for  deeply  decayed  teeth,  making  of, 

150 
Downey,  195 
investing  of,  196 
soldering  of,  196 
gold  for,  372 

built-up  solid  cusp,  173 

making  of,  technic  of,  174 
h'alf  caps,  197 
jacket,  197 

for  anterior  teeth,  197 
for  bicuspids,  199  j 

porcelain,  195  ! 

for  anterior  teeth,  302 
bite  in,  302 

casting    bases    on    abutment 
caps,  306 


Crowns,  porcelain,  for  anterior  teeth, 
casting     bases     on     small 
saddles,  306 
copper  drills  in,  304 
crowns  in,  302 

bases,  making  of,  303 
grinding  of,  302 
impression  in,  302 
retaining  wall  in,  304 
saddle  in,  adjusting  of,  302 
impression  for,  302 
making  of,  302 
shrinking    of    cast    bases    on 

cooling,  305 
tin  foil  in,  use  of,  305 
waxing    bases    to  '  abutment 
caps,  307 
to  saddle,  307 
posts  for,  307 
application  of,  301 
casting  process  in,  301 
deep  saddle,  309 

bases  for,  casting  of,  309 
investing  of,  311 
ring,  casting  of,  310 
soldering  to  cap,  311 

to  saddle,  311 
uniting  of,  310 
waxing  of,  to  cap,  310 
to  saddle,  310 
carving  sides  for  plates,  311 
cementing  crowns  in  place,  313 
finishing  of,  313 
grinding  of,  309 
impressions  for,  312 
models  for,  312 
wall  to  hold  crown  in  place,  309 
waxing  sides  for  plates,  311 
depth  of  bite  for,  301 
faced,  187 

as  abutments  for  extension  sad- 
dle bridges,  314 
backing  of,  192 
finishing  of,  195 
single,  investment  for,  194 
soldering  of,  192,  194 
waxing-up  of,  192 
spatula  for,  194 
investing  of,  196 
limitations  of,  301 
selection  of,  214 
shade  variation  and  blending  of, 

214 
shapes  of,  215 
soldering  of,  196 
top,   as  abutments  for  extension 

saddle  bridges,  314 
types  of,  215 
with  cast  base,  casting  process  in, 

200 
with  soldered  base  in  fixed  bridges, 
221 


IXDEX 


447 


Crowns,    porcelain,     witli     wax    l)ase, 
casting  process  in,  201 
re|)airing  of,  342 
crown  setter  in,  343 
removal  of  caj>  for  porcelain  or 
jrorcelain-faced  crown,  345 
of  i)o.st,  345 

])ost-pxiller  in,  345 
with  drill  and  pliers,  345 
shell  crowns,  343 
replacing  facings,  346 
soldering  facings,  346 
Ivichmond,  187 
l)acking  of,  192 
finishing  of,  195 
single,  investment  for,  194 
soldering  of,  192,  194 
waxing  up  of,  192 
spatula  for,  194 
seamless,  165 

instability  of,  166 
setting  of,  with  gutta-percha,  341 
with  oxyphosphate  of  zinc,  336 
shell,  repairing  of,  342-344 
taking  measurement  of  stump  for, 

173 
telescope,  227 
as  abutments  for  extension  saddle 

bridges,  314 
alloys  for,  227 

Weinstein's,  22H,')iote. 
construction  of,      new     series     of 

alloys  and,  406 
contour  of,  casting  of,  240 
cusps  of,  casting  of,  240 
preparation  of,  238 
.selection  of,  238 
soldering  of,  2.39 
durabilit}'  of,  228 
inner  cap  of,  cutting  bands  for,  229 
fitting  bands  to  .stump,  229 
nicasurcnient  of,  229 
polishing  of,  231 
reinforcing  of,  231 
sweating  floor  to,  230 
outer  cap  of,  burnishing  of,  235 
contour  of,  236 

restoring  of  molars  to,  237 
.shaping  of,  237 
soldering  of,  237 
liquid  flux  for,  236 
finishing  of,  240 
fitting  over  inner,  2.34 
making  of,  233 
measureuK'nt  of,  233 
oj'chjsal  end  of,  filling  of,  235 

filing  of,  235 
removal  of,  from  inner,  235 
sweating  floor  to,  2;{6 
trimming  of,  23(i 
trr(;liiiir-  of,  228 
trimming  tooth  for,  228 


Crowns,  telescope,  with  tube  arul  split 
pins,  241.      See  Crowns,  combina- 
tion, 
window,  197 

with  cast  bases,  attaching  sj)rue  wire, 
224 
posterior,  223 
use  of,  223 

waxing  l)ases  for  casting,  223 
Cusp  buttons,  making  of,  180 

holding  and  filling  base  of,  184-185 
matrix,  filling  of,  with  coin  gold,  183 

swaging  devise  for,  182 
uniting  of,  to  l)and,  185 
Cuspids,  radiosrraphv  of,  position  for, 

415 
Cusps    for    extension    saddle    Ijridges, 
fitting  of,  324 
trimming  of,  325 
for  fixed  bridges,  grinding  of,  217 

.selection  of,  217 
of  lower  bicuspids,  169,  172 
molars,  first,  171 
second,  172 
third,  172 
making  of,  179 

of  telescope  crowns,  preparation  of, 
238 
selection  of,  238 
.soldering  of,  239 
of  upper  bicuspids,  169,  172 
molars,  first,  169 
second,  1()9 
third,  170 


De.nsitv  of  metals,  table  of,  .359 
Dental  bridge,  205.     See  Bridger,  den 
tal. 
caries,  radiograjjiiy  and,  425 
metallurgy,  357 
Dentimeter,    Kirk's,   for  mea.sinement 

of  roots,  187 
Dento-alveolar  abscess,  25 
acute,  treatment  of,  26 

arom,  tic  sulphuric  acid  in,  27 
peroxide  of  hyflrogen  in,  26 
danger  of,  27 
chronic,  treatment  of,  30 
establishing  fistula  in,  28 
locating  apex  of  root  in,  28 
painless  in.sertion   of   hyi)odermic 

needle  in,  29 
root  amputation  in,  .31 
filling  caiia.l  in,  31 
treatment  of  wound  in,  32 
l)c\  it.ilizatioii  of  |)ulp,  '■'>'■'> 
.'igents  u.sed  in,  3(i 
.•irsenic  in,  ,38 
flangei'  of,  39 


448 


INDEX 


Devitalization  of  pulp,  discoloring  of 
teeth  after,  cause  of,  34 
prevention  of,  34 

Dr.  Herman  Prinz's  method,  36 

exceptions  to,  33 

heroic  method  of,  39 

local  anesthesia  in,  44 

novocaine  in,  44 

pressure  anesthesia  in,  41 

sterilization  of  field  of  operation 
in,  42 

treatment  preparatory  to,  41 
Donaldson's  canal  cleaners,  54 
Downey  crowns,  195 

enlarging  pulp  canals  for,  61 

investing  of,  196 

root  facings  for,  113 

soldering  of,  196 
Drawn  tubes,  276 
Drilled  tubes,  276 


E 


Elongation   of   teeth   from   lack   of 

occlusion,  213 
Enamel  cleavers,  118 

scalers,  103 
Evans'  root  drier,  338 
Extension  bridges,  220 
bicuspids,  220 

rule  regarding  supports  for,  221 
small  anterior,  220 
with  saddles,  221 
saddle  bridges,  314 

abutments  necessary  for,  314 
porcelain-faced  crowns,  314 

top  crowns,  314 
telescope  crowns,  314 
adjustment  of,  saddle  to  abut- 
ments, 318 
to  ridge,  314,  317 
buccal  plates,  carving  for,  325 
clamping  to  saddle,  328 
impressions  for,  326 
investing  of,  329 
models  for,  326 
soldering  of,  329 
waxing  for,  325 
contraction  of  gold  in  soldering, 
and  restoring  of  proper  align- 
ment, 321 
cusps  of,  fitting  of,  324 

trimming  of,  325 
facings  for,  backing  of,  324 
bevelling  of,  324 
grinding  of,  323 
selection  of,  323 
with   gold   occlusal   surfaces, 
use  of,  323 
finishing  of,  333 


Extension  saddle  bridges,  fusible  meta 
counterdies   for,  making 
of,  327 
dies  for,  making  of,  327 
grinding  of,  333 
impression  for,  315 
investing  of,  320 

for  final  soldering,  330 
lingual  plates,  carving  for,  325 
impressions  for,  326 
models  for,  326 
soldering  of,  331 

of  bridge  and,  329 
waxing  for,  325 
metal  for,  316 

cleansing  of,  316 
model  for,  315 

preparations  of,  321 
polishing  of,  334 
reinforcing  of,  316 
soldering  to  abutment  caps,  320 
body  to  bridge,  330 
cleansing  after,  332 
drying  after,  332 
trimming  and  waxing  to  abut- 
ment caps,  320 
vulcanite  attachment  for,  322 


Facings,  broken,  replacing  of,  342 
bending  pins  in,  346 
on  bridge  without  removal  from 

mouth,  346 
Bryant  system  of,  350 
cementing  facings  in  place,  346, 

348,  350 
on  crowns  without  removal  from 

mouth,  346 
cutting  out  and  dovetailing  hole 

in  backs,  346 
dovetailing  holes  in  facing,  349 
drilling  out  pins,  carborundum 
in,  348 
glycerin  in,  348 
instruments  for,  348 
fitting  tin  backing  to  facing,  347 
headed  pins  left  in  metal  back- 
ing in,  348 
Peeso's  method  of,  346 
for  extension  saddle  bridges,  323 
for  fixed  bridges,  backing  of,  216 
grinding  of,  216 
selection  of,  216 
interchangeable,  218 
backing  of,  219 
fixed  bridges  and,  finishing  of,  219 

grinding  duplicates,  220 
investing  of,  219 
soldering  of,  219 
selection  of,  214 


INDEX 


449 


Facings,  shade  variation  and  blending 
of,  214 
shapes  of,  215 
tj'pes  of,  215 
Files,  proper  use  of,  176 
Fixed  bridges,  206,  215 

anterior,  backing  of,  218 

interchangeable  facings  and,  fin- 
ishing of,  219 
grinding  duplicates,  220 
common  type  of,  216 
cusps  for,  grinding  of,  217 

selection  of,  217 
facings  for,  backing  of,  216 
grinding  of,  216 
selection  of,  216 
posterior,  investing  of,  217 
waxing-up  of,  217 
Floors,  construction  of,  new  series  of 
alloj-s  and,  405 
drilling  of,  for  post  or  pin,  189 
flattening  of,  swaging  devise  for,  188 
sweating  of,  to  band,  189 
Fluxes,  400 

for  casting,  400  ' 
oxidizing  of,  403 

formula  for,  403 
reduction  of,  402 

formula  for,  402 
for  soldering,  400 

formula  for,  401,  404 
Formalin  in  treatment  of  putrescent 

pulp  canals,  24 
Fractured  roots,  treatment  of,  68 
Fusible  metal,  232 

dies  and  counterdies  for  extension 
saddle  bridges,  327 


Gates-Glydden  nerve  canal  drills,  58 
Gold,  alloys,  compounding  of,  3S3 

melting  points  of,  362,  363,  364 
for  bridge-work,  372 
cleansing  of,  163 

hydrochloric  acid  in,  163 

saturated  solution  of  alum  in,  163 

sulphuric  acid  in,  163 
coin,  fining  cusp  matrix  with,  183 
copper  alloy  and,  165 
for  crowns,  372 
deoxidizing  of,  163 
for  inlay  casting,  375 
formula  for,  377 
iridium  alloys  and,  360 
osmium  alloys  and,  300 
palladium  alloys  and,  366 

f)latinized,  spUt  pins  of,  285 
or  i)late  work,  372 
platinum  alloys  and,  364 
rhodium  alloys  and,  370 

29 


Gold,  silver  alloy  and,  165,  360 
solders,  381 

alloys  for,  382 
U.  S.  coin,  165 
caret  of,  228 
properties  of,  228 
Gums,  protection  of  stumps  from  en- 
croachment of,  126 
Gutta-percha    points    in    filling   pulp 
canals,  62 
setting  of  crowns  with,  341 
technic  of,  341 


Half  caps  or  crowns,  197 

round  wke  split  pins,  284 
Hammer-headed  hand-vise,  278 
Heroic  method  of  devitahzing  pulp,  39 
Hydrochloric  acid,  use  of,  in  cleansing 

gold,  163 


Impacted  teeth,  radiography  and,  426 
Imperfectly  formed  teeth,  radiography 

and,  426 
Impressions,  120 

and  model,  separating  of,  140 

and  articulation  with  face  bow,  134 

artificial  stone,  Weinstein's,  120 

bite  and,  122 

of  broken-down  roots,  taking  of,  144 

teeth,  taking  of,  144 
plaster,  120 

of  Paris,  coloring  of,  123 

carmine  solution,  preparation 
of,  123 
flavoring  of,  123 

cologne  solution,  preparation 
of,  123 
mixing  of,  124 
removal  of,  from  mouth,  126 
in  sections,  129 

dovetailed  spaces  in,  132 
of  lower  anterior  teeth,  130 
of  teeth  lingually  inclined,  131 
undercuts  in,  132 
treatment  of,  126 
separating  medium  in,  128 
tough  adhesive  wax  in,  127 
waxing  in  bands  in,  127 

in  caps  in,  127 
with  abutments  in  place,  taking  of, 
125 
Inlay  abutments,  260 

for  anterior  teeth,  261 

attaching  sprue  wire  in,  262 
building   inlay    in    wax   with 

tube  in  place,  262 
casting  of,  262 


450 


INDEX 


Inlay   abutments    for   anterior    teeth, 
enlarging  canal  for,  261 
filling  pure  gold  matrix  with 

coin  gold,  266 
finishing  of,  267 

of  cavity  for  second  inlay, 
.  264 
fitting    tube    with    asbestos 

paper  in,  262 
flaskmg  of,  262 
impression  with  inlay  in  place, 

283 
investing  of,  266,  267 
poUshing  inlay  in,  267 
preparation  of  cavity  for  sec- 
ond inlay,  263 
of  model  for,  263 
removal    of    tube    with    wax 

inlay  from  mandrel,  262 
second  inlay,  making  of,  265 
shaping  of  cavity  for,  261 
soldering  with  bridge,  267 
waxing  of,  287 
construction    of,    new    series    of 

alloys  and,  406 
indications  for,  260 
matrix,  271 

pure  gold  or  platinum  foil,  271 
for  molars,  267 

cavity  in,  depth  of,  for  tubes, 
267 
for  final  inlay,  270 
preparation  of,  267 
cementing  of,  270 
final  inlay  in,  270 
finishing  of,  270 
matrix  in,  casting  of,  268 

preparation  of,  for  impression, 

268 
securing  of,  268 
model  for,  preparation  of,  269 
second  inlay  in,  carving  of,  269 
casting  of,  269 
soldering  of,  to  pure  gold 

matrix,  270 
waxing  of,  269 
tube  in,  adjusting  of,  269 
parallehng  of,  269 
for  removable  bridges,  cementing 

of,  339 
for  small  bridges,  271 
where  indicated,  272 
Inner  caps,  construction  of,  new  series 

of  alloys  and,  405 
Interchangeable  facings,  218 

anterior  fixed  bridges  and,  finish- 
ing of,  219 
grinding  duplicates,  220 
backing  of,  219 
investing  of,  219 
soldering  of,  219 
Investing  of  combination  crowns,  244 


Investing  of  Downey  crowns,  196 
of  interchangeable  facings,  219 
of  porcelain  crowns,  196 
Investment  compounds  for  casting,  392 
formula   for,    396 
hot  or  cold  mould  in,  394,  395 
for  soldering,  385 
formula  for,  391 
materials,  compounding  of,  397 
for  single  porcelain-faced  crowns,  194 
Investments,  directions  for  uses  of,  397 

heating  of,  398 
Iridio-platinum  tubes,  276 

.    wire  split  pins,  284 
Iridium  alloys,  gold  and,  369 
Irregularities  of  teeth,  slight,  152-153 
treatment  of,  152-158 


Jacket  crowns,  197 

for  anterior  teeth,  197 

for  bicuspids,  199 
Jaw,  lower,  teeth  of,  relative  strength 

of,  72 
upper,  teeth  of,  relative  strength  of, 

72 


Kerr  broaches    in    opening  of    pulp 

canals,  47 
Key  and  shoe,  attaching  key  to  crown, 
250 
completion  of  shoe,  251 
constructing  bridge,  251 
making  of,  250 
preparing  crown  for  key,  250 
Kirk's  dentimeter,  for  measurement  of 
roots,  187 


Lead    box    for   protecting   unexposed 
radiograph  films,  412 
glass   diaphragm  for.  use  in  radiog- 
raphy, 411 
Lower  anterior  roots,  trimming  of,  107 
teeth,  impressions  of,  in  sections, 
130 
bicuspids,  cusps  of,  172 
characteristics  of,  169 
pulp  canals  of,  52 
trimming  of,  96 
jaw,  teeth  of,  relative  strength  of,  72 
molars,  first,  cusps  of,  171 
pulp  canals  of,  49 
second,  cusps  of,  172 
third,  cusps  of,  172 
trimming  of,  83,  94 


INDEX 


451 


M 


Mandrel  process  of  making  tubes,  277 
Matrix  method  of  inlaj-  abutments,  271 
Maxillary  sinus,  radiography  of,  posi- 
tions for,  416,  422 
Melting  points  of  binary  alloys,  368 
of  clasp  metals,  379 
of  gold  and  copper,  364 
and  palladium,  366 
and  platinum,  365 
and  sUver,  362 
of  metals,  table  of,  359 
of  new  series  of  alloys,  405 
of  standard  dental  goods,  405 
Metal,  fusible,  232 
Metallurgj^,  dental,  357 
Metals,  clasp,  378 

composition  of,  379 
melting  point  of,  379 
densities  of,  table  of,  359 
melting  points  of,  table  of,  359 
Models,  120 
of  broken-down  roots,  preparation  of, 
144 
teeth,  preparation  of,  144 
casting  of,  138 

for  deeply  decayed  teeth,  149 
for  extension  saddle  bridges,  315 
for  inlay  abutments  for  molars,  269 
plaster,  120 

making  articulating  surfaces,  138 
of  roots  broken  below  gum  line,  pre- 
paration of,  145 
decaj-ed  below  gum  line,  prepara- 
tion of,  145 
working,  drj^ing  out  of,  141 
hardening  of,  142 
preparation  of,  140 
trimming  of  stumped,  141 
Molars,  impacted,  radiography  of,  posi- 
tion for,  420 
inlay  aljutments  for,  267 

cavity  in,  depth  of,  for  tubes, 
267 
for  final  inlay,  270 
I)reparation  of,  267 
ceinentiiig  o!,  270 
final  inlay  in,  270 
finishing  of,  270 
matrix  in,  casting  of,  268 

preparation  of,  for  impression, 

268 
securing  of,  268 
model  for,  preparation  of,  269 
KCcon<i  inlay  in,  carving  of,  269 
casting  of,  269 
soldering  of,   to  pure  gold 

matrix,  270 
waxing  of,  269 
tul^  in,  adjusting  of,  269 
paralleling  of,  269 


Molars,  lower,  first,  cusps  of,  171 
pulp  canals  of,  49 
second,  cusps  of,  172 
third,  cusps  of,  172 
tilted  forward,  trimming  of,  94 
trimming  of,  83 

instruments  for,  84 

principal  cuts  in,  89 
upper,  first,  cusps  of,  169 
pulp  canals  of,  47 
second,  cusps  of,  169 
third,  cusps  of,  170 
trimming  of,  97 

principal  cuts  in,  98 


N 

Necrosis,  radiography  and,  426 
Novocaine  in  devitaUzation  of  pulp,  44 


Occlusion,  211 

teeth  elongated  from  lack  of,  213 
Orthodontia  and  prosthodontia,  rela- 
tion of,  151 
Osmium  alloys,  gold  and,  369 
Ottolengui's  root  facers,  118 
Oxidizing  of  flux,  403 
formula  for,  403 
Oxyphosphate  of  zinc,  336 

cementing  fixed  bridges  with,  337 
characteristics  of,  336 
mixing  of,  336 

spatula  for,  336 
setting  crowns  with,  336 


Palladium,  alloys  of,  melting  points  of, 

366 
Pathological  conditions,  relation  of,  to 

crown  and  bridge-work,  22 
Peeso's  method  of  repairing  broken  fac- 
ings, 346 
root  reamer,  59 

system  of   crown  and  bridge-work, 
application  of  new  scries  of  alloys 
to  405 
Perforated  roots,  treatment  of,  66 
Peroxide  of  hydrogen  in  treatment  of 

dento-alveolar  abscess,  26 
Pins,  crown,  soldering  and  cap,  192 
Plaster  articulators,  135 
making  of,  135 
impressions,  120 
models,  120 
of  Paris,  coloring  of,  1 23 

carmine  solution  in,  preparation 
of,  123 
flavoring  of,  123 


452 


INDEX 


Plaster  of  Paris,  flavoring  of,  cologne 
solution  in,  preparation  of,  123 
properties  of,  389       , 
Plate  for  tubes,  278 
Plates,  articulating,  138 
Plate  work,  gold  for,  372 
Platinized  gold  split  pins,  285 
Platinum,  aUoys  of,  melting  points  of, 

365 
Pliers,  collar,  use  of,  in  shaping  bands, 
175 
contouring,  160 
pin  roughing  and  bending,  193 
stretching,  160 
Porcelain  bridges,  151 
crowns,  195 

for  anterior  teeth,  302 
bite  in,  302 

casting    bases    on    abutment 
caps,  308 
on  small  saddles,  306 
copper  driUs  in,  304 
crown    bases   in,  making  of, 
303 
grinding  of,  302. 
impression  in,  302 
retaining  wall  in,  304 
saddle  in,  adjusting  of,  302  ■ 
impression  for,  302 
making  of,  302 
shrinking    of    cast    bases    on 

cooUng,  305 
tin  foil  in,  use  of,  305 
waxing    bases    to    abutment 
cap,  307 
to  saddle,  307 
posts  for,  307 
application  of,  301 
casting  process  in,  301 
deep  saddle,  309 

bases  for,  casting  of,  309 
investing  of,  311 
ring,  casting  of,  310 
soldering  to  cap,  311 

to  saddle,  311 
uniting  of,  310 
waxing  of,  to  cap,  310 
to  saddle,  310 
carving  sides  for  plates,  311 
cementing    crowns    in    place, 

313 
finishing  of,  313 
grinding  of,  309 
impressions  for,  312 
models  for,  312 
wall  to  hold  crown  in  place, 

309 
waxing  sides  for  plates,  311 
depth  of  bite  for,  301 
enlarging  pulp  canals  for,  59,  61 
investing  of,  196 
limitations  of,  301 


Porcelain  crowns,  root  facing  for,  113 
selection  of,  214 
shade  variation  and  blending  of, 

214 
shapes  of,  215 
soldering  of,  196 
tjrpes  of,  215 

with  cast  base,  casting  process  in, 
200 
for  removable  bridges,  301. 
with  soldered  base  in  fixed  bridges, 

221 
with  wax  base,  casting  process  in, 
201 
faced  crowns,  187 

as     abutments     for     extension 

saddle  bridges,  314 
backing  of,  192 
finishing  of,  195 
single,  investment  for,  194 
soldering  of,  192,  194 
waxing-up  of,  192 
spatula  for,  194 
Portable  dark-room  box  for  developing 

radiograph  film,  413 
Post-puller,  345 

Potassium  in  enlarging  of  pulp  canals, 
48 
in    treatment    of    putrescent    pulp 
canals,  23 
Powdered  sUex,  properties  of,  389 
Prinz,  Dr.  Herman,  method  of  divital- 

izing  pulp,  36 
Prosthesis,  157 

Prosthetic  castings,  gold  for,  374 
Prosthodontia  and  orthodontia,  rela- 
tion of,  151 
Pulp  canals  of  anterior  teeth,  52 
cleansing  of,  54 
instruments  for,  54 
Donaldson's,  54 
sterilization  of,  55 
methods  of,  55 
superheated  steam  in,  56 
constricted,  50 

for  all  porcelain  crowns,  61 
for  Downey  crowns,  61 
enlarging  of,  Gates-Glydden  nerve 
canal  drills  in,  58 
instruments  for,  58 
Peeso's  root  reamer  in,  59 
for  porcelain-faced  crowns,  59 
potassium  in,  48 
sodium  in,  48 
dioxide  in,  48 
filling  of,  62 

gutta-percha  points  in,  62 
materials  for,  62 
location  of,  46 
of  lower  bicuspids,  52 

molars,  49 
opening  of,  instruments  for,  47 


INDEX 


453 


Pulp  canals,  opening  of,  Kerr  broaches 
in,  47 
putrescent,  sterilizing  of,  23 
treatment  of,  23 
formalin  in,  24 
potassium  in,  23 
sodimn  in,  23 
dioxide  in.  23 
removal  of  pulp  from,  54 
sensitiveness  after,  57 
tenderness  after,  57 
tortuous,  50 
of  upper  bicuspids,  51 

molars,  47 
with  enlarged  foramina,  filling  of, 

63 
work,  x-rays  in,  52 
chamber,  opening  into,  46 
exposure  of,  radiography  and,  425 
infection,  treatment  of,  24 
Pulps,  aching,  treatment  of,  prepara- 
tory^ to  devitalizing,  41 
ilevitalization  of,  33 
agents  used  in,  36 
arsenic  in,  38 

danger  of,  39 
discoloring  of  teeth  after,  cause  of, 
34 
prevention  of,  34 
Dr.  Herman  Prinz's  method,  36 
exceptions  to,  33 
heroic  method  of,  39 
local  anesthesia  in,  44 
novocaine  in,  44 
pressure  anesthesia  in,  41 
sterilization  of  field  of  operation 

in,  42 
treatment  i)reparatory  to,  41 
formative  organs  of,  33 
inflamed,  treatment  of,  preparatory 

to  devitaUzing,  41 
vitality  of,  33 
Putrescent  pulp  canals,  sterilizing  of,  23 
to  treatment  of,  23 
formaUn  in,  24 
pfjtassium  in,  23 
sodium  in,  23 
dioxide  in,  23 
Pyorrhea  alveolaris,  radiography  and, 
436 
relation  of,  to  crown  and  bridge-work, 
22 
Pyorrheal   conditions,    relation   of,    to 
crown  and  bridge-w(jrk,  23 


Radiograph  in  crown  and  bridge-work, 

408 
abHcosH  and,  428 
anorrialif«  in   direction  of  roots 

and,  434 


Radiograph  in  crown  and  bridge-work, 
anomalies   in  number  of   roots 
and,  434 
in  shape  of  roots  and,  434 
dangers  of,  to  operator,  423 

to  patient,  423 
dental  caries  and,  425 
for  diagnosing  field  of  operation, 

409 
foreign  bodies  and,  437 
fractured  roots  and,  431 
ill-fitting  crown  and  bridges  and, 

438 
impactions  and,  426 
imperfectly   formed    teeth   and, 

426 
indications  for  use  of,  424 
measiu'ing  roots  and,  433 
necrosis  and,  426 
outfit  for,  410 

position  for  making  exposures  of 

cuspid  and  lateral,  415 

of    four    upper    anterior 

teeth,  417 
of  impacted  lower  third 

molars,  420 
of  lower  anterior  teeth, 

418 
of  maxillary  sinus,  421 
of  teeth  posterior  to  lower 

first  bicuspid,  419 
of  upper  right  teeth,  416 
proximity  of  roots  to  maxillary 

sinus  and,  434 
pulp  exposure  and,  425 
pyorrhea  alveolaris  and,  436 
records  of,  interpretation  of,  410 

keeping  of,  410 
retained  teeth  and,  426 
root  absorption  and,  424 

fragments  and,  435 
root-canal  fillings  and,  426 
technic  of,  410 
unerupted  teeth  and,  426 
dental,  literature  on,  410 
frosted  white  and  ruby  lamp,  use  of 

in,  414 
lead  box  for  protecting  unexposed 
films.  412 
glass  diaphragm  for  use  in,  411 
portable  dark-room  box  for  develop- 
ing films,  413 
Refractory  materials,  385 
Itcmovable    l)ridges,    206,    225.      See 

Bridges,  removable. 
Rei)airing  crowns,  342.     See  Crowns, 

repairing  of. 
Retained  tc-eth,  radiography  and,  426 
RetiJ.ining  media,  336 

cementing  of  fixed  bridges,  337 

of  nimovable  bridges,  339 
gutta-pcsrclia,  341 


454 


INDEX 


Retaining  media,  oxyphosphate  of  zinc, 

336 
Rhodium  alloys,  gold  and,  370 
Richmond  crowns,  187 
backing  of,  192 
finishing  of,  195 
root  facing  for,  112 
single,  investment  for,  194 
soldermg  of,  192,  194 
waxing-up  of,  192 
spatula  for,  194 
Rigg's  disease,  bridge-work  for,  351 
split  bar  for  special  cases,  354 
Stewart  on,  351 

tubes  swung  off  side  for  abut- 
ment crowns,  355 
types  of  attachments,  352 
variations  of  split  pin  and  split 
bar  in,  351 
Root  absorption,  radiography  and,  424 
amputation,  31 
facers,  Ottolengui's,  118 
reamer,  Peeso's  59 
Roots,  anomalies  of,  radiography  and, 
434 
broken  apart,  treatment  of,  71 
below  gum,  fitting  bands  to,  145 

models  of,  preparation  of,  145 
down,  building  up,  with  amalgam, 
143 
decayed  below  gum,  fitting  bands  to, 
145 
models  of,  preparation  of,  145 
facing  for  Downey  crowns,  113 
for  porcelain  crowns,  113 
in  removable  attachment  for  an- 
terior teeth,  252 
for  Richmond  crowns,  112 
fractured,  radiography  and,  431 

treatment  of,  68 
fragments  of,  radiography  and,  435 
lower  anterior,  trimming  of,  107 

instruments  for,  107 
measurement  of,  dentimeter  for,  187 
measuring  of,  radiography  and,  433 
perforated,  treatment  of,  66 
proximity  of,     to    maxillary    sinus, 

radiography  and,  434 
separated,  treatment  of,  71 
upper  anterior,  trimming  of,  102 
instruments  for,  102 


Saddle   bridges,    abutments   at   both 
ends,  anterior,  334 
deep,  309 

bases  for,  casting  of,  390 
investing  of,  311 
ring,  casting  of,  310 
soldering  to  cap,  311 
to  saddle,  311 


Saddle  bridges,  deep  bases  for,  uniting 
of,  310 
waxing  of,  to  cap,  310 
to  saddle,  310 
carving  sides  for  plates,  311 
cementing  crowns  in  place,  313 
finishing  of,  313 
grinding  of,  309 
impressions  for,  312 
models  for,  312 

wall  to  hold  crown  in  place,  309 
waxing  sides  for  plates,  311 
extension,  314 

abutments  necessary  for,  314 
porcelain-faced  crowns,  314 

top  crowns,  314 
telescope  crowns,  314 
adjustment  of  saddle  to  abut- 
ments, 318 
to  ridge,  314,  317 
buccal  plates,  carving  for,  325 
clamping  to  saddle,  328 
impressions  for,  326 
investing  of,  329 
models  for,  326 
soldering  of,  329 
waxing  for,  328 
contraction  of  gold  in  soldering 
and  restoring  of  proper  align- 
ment, 321 
cusps  of,  324,  325 
facings  for,  backing  of,  324 
beveling  of,  324 
grinding  of,  323 
selection  of,  323 
with   gold   occlusal   surfaces, 
use  of,  323 
finishing  of,  333 
fusible    metal   counterdies    and 

dies  for,  327 
grinding  of,  333 
impression  for,  315 
investing  of,  320 

for  final  soldering,  330 
lingual  plates,  carving  for,  325 
impressions  for,  326 
models  for,  325 
soldering  of,  331 

bridge  and,  329 
waxing  for,  325 
model  for,  315 
polishing  of,  334 
reinforcing  of,  316 
soldering  to  abutment  cap,  320 
of  body  to  bridge,  330 
cleansing  after,  332 
drying  after,  332 
trimming  and  waxing  to  abut- 
ment caps,  320 
vulcanite  attachments  for,  322 
Saddles,  construction  of,  new  series  of 
alloys  and,  407 


INDEX 


455 


Saddles  in  porcelain  crowns  for  anterior 

teeth,  302 
Scalers,  enamel,  103 
Shears,  curved,  168 
straight,  168 

use  of,  in  festooning  band,  167 
Shell  crowns,  repairing  of,  342-344 
Silex,  powdered,  properties  of,  389 
Silver,  alloj's  of,  melting  points  of,  362 
Sodium  dioxide  in  enlarging  of  pulp 
canals,  48 
in  treatment  of  putrescent  pulp 
canals,  23 
in  enlarging  of  pulp  canals,  48 
in    treatment    of    putrescent    pulp 
canals,  23 
Soldered  joint  bands,  164 
Soldering,  autogenous,  159 

of  buccal  plates  on  extension  saddle 

bridges,  329 
in  cap"  in  split  pins  used  on  teeth  of 

divergent  angles,  299 
of  combination  crown  in  tube,  244 
of  cusps  of  telescope  crowns,  239 
of  Downej^  crowns,  196 
of  extension  saddle  bridges,  330 
fluxes  for,  400 

formula  for,  401,  404 
of  inlay  abutments  for  anterior  teeth 

with  bridge,  267 
of  interchangeable  facings,  219 
investment  compounds  for,  385 

formula  for,  391 
of  lingual  plates  on  extension  saddle 

l)ridges,  331 
of  porcelain  crowns,  190 
of  split  pins,  287 

to  cap,  249 
of  tubes,  281 

used  on  teeth  of  divergent  angles, 
299 
sweating  process,  159 
advantages  of,  159 
Solders,  gold,  381 

alloys  for,  382 
Spatula  for  mixing  oxy phosphate   of 
zinc,  33li 
for   waxing  porcelain-faced   crowns, 
194 
Richmond  crowns,  194 
Split  pins,  284 
alloy  for,  284 
burnishing  of,  290 
clasp  wire,  285 

rniarging  necks  for,  247  I 

filing  of,  287  j 

file  and  pin  vise  in,  use  oi,  288 
(j])(:u  at  end,  291 
fitting  of,  into  tubes,  217 
forging  h.alves  in  «)ntact,  287 
half-roiirid  wire,  284 
haiiiniering  halvr;H  in  contact,  287 


Split  pins,  iridio-platinum  wire,  284 
long,  closed  at  end,  291 
making  of,  technic  of,  286 
platinize!  gold,  285 
removable  attachment  for  anterior 

teeth,  investing  of,  255 
smoothing  of,  290 
soldering  of,  287 

to  cap,  249 
solid  pin  sawn  through,  weakness 

of,  384 
use  of,  reversal  of  usual  type,  297 
on  teeth  of  divergent  angles,  298 
bands  in,  fitting  of,  298 
fitting  in  cap,  299 
impressions  in,  298 
making  outer  half  cap,  299 
models  for,  298 
roots  in,  preparation  of,  298 
soldering  in  cap,  299 
Weinstein's  devices  for,  292 
Sterilizing  putrescent  pulp  canals,  23 
Stewart,   Howard  J.,   on    bridge-work 

for  Rigg's  disease  conditions,  351 
Stretching  pliers,  160 
Stumps,  protection  of,  from  encroach- 
ment of  gums,  126 
Sulphuric  acid,  aromatic,  in  treatment 

of  dento-alveolar  abscess,  27 
Supporting  abutments,  272 
Swaging  device  for  cusp  matrices,  182 

for  flattening  floors,  188 
Sweating  of  bands,  163 
Syringe,  cement,  340 


Teeth,    anterior.     See    also    Anterior 
Teeth, 
banded  crowns  for,  187 
jacket  crowns  for,  197 
broken-down,  impressions  of,  taking 
of,  144 
models  of,  preparation  of,  144 
decayed,  crowns  for,  making  of,  105 
impression  of,  148 
models  of,  149 
preparation  of,  147 
discoloration  of,  after  devitalization 
of  pulp,  cause  of,  34 
))rcvention  of,  34 
elongation  of,  from  lack  of  occlusion, 

213 
impacted,  radiography  and,  426 
imperfectly  formed,  radiography  and, 

426 
irregularities  of,  slight,  152-1,53 

troaimoiit  of,  1.56-158 
lingually  inclined,  impressions  of,  in 

.sections,  131 
loose,    relation    of,    to    crown    and 
bridge-work,  22 


456 


INDEX 


Teeth,  lower  anterior,  impressions  of,  in 
sections,  130 
of  lower  jaw,  relative  strength  of,  72 
necrosis  of,  radiography  of,  426 
retained,  radiography  of,  426 
as  supports  for  bridge-work,  relative 

strength  of,  72 
trimming  of,  for  bands,  82 

for  caps,  82 
typical  shapes  of,  78 
unerupted,  radiography  of,  426 
of  upper  jaw,  relative  strength  of,  72 
Telescope  crowns,  227 

as  abutments  for  extension  saddle 

bridges,  314 
alloys  for,  227 

Weinstein's,  228,  note. 
construction    of,    new    series    of 

alloys  and,  406 
contour  of,  casting  of,  240 
cusps  of,  casting  of,  240 
preparation  of,  238 
selecting  of,  238 
soldering  of,  239 
durabihty  of,  228 
inner  cap  of,  cutting  bands  for,  229 
fitting  bands  to  stump,  229 
measurement  of,  229 
polishing  of,  231 
reinforcing  of,  231 
sweating  floor  to,  230 
outer  cap  of,  burnishing  of,  235 
contour  of,  231 
finisliing  of,  240 
fitting  over  inner,  234 
making  of,  233 
measurement  of,  233 
occlusal  end  of,  235 
removal  of,  from  inner,  235 
sweating  floor  to,  236 
trimming  of,  236 
technic  of,  228 
trimming  tooth  for,  228 
with  tube  and  split  pins,  241 
Tin,    fitting    to   backing   in   repairing 
broken  facings,  347 
foil,  use  of,  in  porcelain  crowns  for 
anterior  teeth,  305 
Tubes,  alloys  for,  276 

contraction  of,  on  soldering,  247 

drawn,  276 

drilled,  276 

entrance  of,  countersinking  of,  247 

filing  of,  283 

fitting  of,  in  combination  crowns,  243 

split  pins  into,  247 
in  inlay  abutments  for  molars,  269 
iridio-platinum,  276 
making   of,    hammer-headed    hand- 
vise  in,  278 
by  mandrel  process,  276 


Tubes,  making  of,  technic  of,  280 
plate  for,  278 
in  removable  attachment  for  anterior 

teeth,  enlarging  entrance  to,  254 
rounding  end  of,  283 
sizes  of,  284 
soldering  of,  281 

of  combination  crown  in,  244 
of  floor  of,  283 
trimming  of,  283 

use  of,  reversal  of  usual  type,  297 
on  teeth  of  divergent  angles,  298 
adjusting  of,  299 
bands  in,  fitting  of,  298 
impressions  in,  298 
models  for,  298 
roots  in,  preparation  of,  298 
soldering  of,  299 


Unerupted    teeth,  radiography    and, 

426 
Upper  anterior  roots,  trimming  of,  102 
bicuspids,  cusps  of,  172 

pulp  canals  of,  51 

trimming  of,  101 
jaw,  teeth  of,  relative  strength  of,  72 
molars,  first,  cusps  of,  169 

pulp  canals  of,  47 

second,  cusps  of,  169 

third,  cusps  of,  170 

trimming  of,  97 
right  teeth,  radiography  of,  position 

for,  416 

W 

Wax,  tough  adhesive,  use  of,  in  impres- 
sions, 127 
Weinstein's  alloy  for  telescope  crowns, 
228,  note. 
artificial  stone,  120 

impressions  with,  filling  of,  121 
preparation  of,  121 
separation  of,  122  ' 

device  for  making  split  pins,  292 
drawing  wire,  293 
finishing,  295 
pohshing,  295 
swaging,  295    . 
paralleling    device    for    abutments, 
208 
Window  crowns,  197 

X 

X-rays  in  crown  and  bridge-work,  408 


Zinc,  oxyphosphate  of,  336 


E^te 


RK666  P^4 

Peeso 

Jrown  and  bridge  work 


MAY  31  1943  A  '^  .V<_^iA.c^ 


